Gender & Sex

BIOLOGY, IDENTITY, LANGUAGE, AND PUBLIC POLICY

INTRO & DISCLAIMER

• •
  How researchers define and measure sex, gender, gender identity, and intersex traits
• •
  What chromosomes, genes, gonads, hormones, anatomy, and gametes each contribute to human sex development
• •
  What brain research can and cannot establish about gender identity
• •
  Research on social transition, discrimination, bathrooms, sports, pronouns, and LGBTQ-inclusive education
• •
  Commonly cited studies whose methods or conclusions require additional context

• •
  How reproductive biology classifies males and females
• •
  How sex traits develop and vary within human bodies
• •
  How people understand, express, and live their gender

OPENING STATEMENT

KEY OBJECTIONS

“There are only two sexes because there are only two gametes.”

“Chromosomes determine whether someone is male or female.”

“Intersex conditions do not create a third gamete.”

“Sex is immutable.”

“What is a woman?”

“Being transgender is a mental disorder.”

“Brain scans prove that trans people have male or female brains.”

“Trans women always retain an unfair athletic advantage.”

“Trans-inclusive bathroom rules make women less safe.”

“Singular they is grammatically incorrect.”

IMPORTANT STUDIES AND SOURCES

DEFINITIONS & FRAMEWORK

Measuring Sex, Gender Identity, and Sexual Orientation

Methodology

• •
  A multidisciplinary committee reviewed existing measures and research across clinical, administrative, and survey settings.
• •
  Committee members developed consensus definitions and evaluated how different questions perform in different contexts.

Findings

• •
  The report defines sex as a multidimensional construct based on a cluster of anatomical and physiological traits, including external genitalia, secondary sex characteristics, gonads, chromosomes, and hormones.
• •
  The report defines gender as including identity, expression, and social position.
• •
  The committee concluded that gender cannot be reduced to sex assigned at birth or to specific sex traits.
• •
  The report recommends collecting the information required for the purpose at hand. It supports a two-step approach using sex assigned at birth and current gender when researchers need to identify transgender experience.
• •
  The report recommends a separate intersex-status question when that information matters. It advises against treating intersex as a simple third response to a male-or-female sex question.

Limitations

• •
  The report addresses measurement and conceptual clarity. It does not settle every philosophical dispute about the meaning of sex or gender.
• •
  Recommended questions can require revision as terminology and evidence develop.

World Health Organization: Gender and Health

What the source establishes

• •
  Sex refers to biological and physiological characteristics such as chromosomes, hormones, and reproductive organs.
• •
  Gender refers to socially constructed norms, roles, and relations.
• •
  Gender identity refers to a person’s deeply felt internal experience of gender, which may or may not correspond to physiology or designated sex at birth.
• •
  Sex, gender, and gender identity can each influence health and access to care.

Limitations

• •
  This is institutional guidance rather than an original empirical study.
• •
  Definitions vary somewhat across fields, so debates should identify whether the context is clinical, demographic, biological, or social.

American Psychological Association: Understanding Transgender People, Gender Identity and Gender Expression

What the source establishes

• •
  Gender identity describes a person’s internal sense of gender.
• •
  Gender expression describes how a person presents gender through appearance and behavior.
• •
  Transgender describes people whose gender identity differs from the sex assigned to them at birth.
• •
  Gender identity, gender expression, and sexual orientation describe separate concepts.

Limitations

• •
  The page summarizes professional guidance and research. Use its linked scholarship for contested causal claims.

SEX DEVELOPMENT, CHROMOSOMES & INTERSEX VARIATION

Sex Redefined

Methodology

• •
  This is a science-journalism feature based on interviews and published research.
• •
  It follows sex development across chromosomes, genes, gonads, hormones, anatomy, and cells.

Findings

• •
  Typical XX and XY development accounts for most people, while variations can produce discordance among chromosomal, gonadal, hormonal, and anatomical traits.
• •
  Genetic changes, mosaicism, chimerism, hormone production, and hormone-response differences can affect the developmental pathway.
• •
  A single chromosome test cannot describe every sex-related trait in every person.

Limitations

• •
  The article provides a synthesis for general readers. It is not a primary prevalence study.
• •
  The article uses “spectrum” as a broad description of trait variation. Reproductive biology still recognizes two gamete types.

How Sexually Dimorphic Are We? Review and Synthesis

Methodology

• •
  The authors reviewed medical literature on chromosomal, gonadal, hormonal, and anatomical variation.
• •
  They combined prevalence estimates for conditions that departed from an ideal of complete sexual dimorphism.

Findings

• •
  The authors estimated that about 1.7% of live births show some departure from complete chromosomal, gonadal, genital, or hormonal dimorphism under their broad definition.
• •
  The estimate became the main source for the widely repeated 1.7% figure.

Limitations

• •
  Late-onset congenital adrenal hyperplasia contributes most of the estimate. Many people counted by the paper have unambiguous genitalia and identify as male or female.
• •
  The paper’s category is broader than definitions centered on ambiguous genitalia or discordance between chromosomal and phenotypic sex.
• •
  The number should always appear with the definition used to produce it.

How Common Is Intersex? A Response to Anne Fausto-Sterling

Methodology

• •
  Sax reanalyzed the conditions included in the 1.7% estimate.
• •
  He limited “intersex” to conditions involving genital ambiguity or inconsistency between chromosomal sex and phenotypic sex.

Findings

• •
  Sax estimated a prevalence of about 0.018%, or roughly 1 in 5,500 people, under his narrower definition.
• •
  Removing late-onset congenital adrenal hyperplasia accounts for most of the difference between the estimates.

Limitations

• •
  The restricted definition excludes several congenital sex-trait variations included by intersex organizations and other researchers.
• •
  The disagreement concerns classification as well as arithmetic. The 0.018% and 1.7% figures describe different sets of conditions.

SRY Gene: MedlinePlus Genetics

What the source establishes

• •
  SRY usually appears on the Y chromosome and helps direct development of the testes.
• •
  SRY variants account for a portion of 46,XY complete gonadal dysgenesis, also called Swyer syndrome.
• •
  An SRY translocation onto an X chromosome can contribute to 46,XX testicular differences of sex development.

Limitations

• •
  SRY provides one part of a larger pathway that includes many genes, hormones, receptors, and tissues.
• •
  The page provides clinical orientation rather than prevalence estimates for every condition.

Swyer Syndrome: MedlinePlus Genetics

What the source establishes

• •
  People with Swyer syndrome have a 46,XY karyotype and female-typical external genitalia.
• •
  They usually have a uterus and fallopian tubes because typical testicular hormone production did not occur during development.
• •
  Their gonads do not function as ovaries, so pregnancy requires donated oocytes and medical support.

Limitations

• •
  Swyer syndrome is rare.
• •
  The condition demonstrates variation in sex development. It does not show that chromosomes lack biological importance.

Pregnancy and Delivery in a Patient With Pure 46,XY Karyotype

Methodology

• •
  The authors described a patient with 46,XY complete gonadal dysgenesis who became pregnant through in vitro fertilization using a donated oocyte.
• •
  They reviewed previous reports of pregnancy in patients with 46,XY gonadal dysgenesis.

Findings

• •
  The patient carried a pregnancy and delivered a healthy child.
• •
  The case documents that a Y chromosome does not prevent gestation when a uterus is present and assisted reproduction supplies an oocyte and hormonal support.

Limitations

• •
  This is a rare case report rather than a prevalence study.
• •
  The patient did not produce an oocyte, and the case does not establish typical fertility for people with Swyer syndrome.

GENDER DEVELOPMENT & NEUROSCIENCE

Patterns of Gender Development

Methodology

• •
  The authors reviewed research on children’s gender concepts, identity, stereotypes, preferences, and behavior.
• •
  The review considered cognitive development, motivation, social learning, family, peers, and culture.

Findings

• •
  Children actively organize information about gender and apply it to themselves and other people.
• •
  Gender development reflects interactions among cognition, motivation, social environment, and biological development.
• •
  Children develop gender labels before they develop a complete understanding of gender stability and constancy.

Limitations

• •
  Much of the literature comes from Western populations.
• •
  The review addresses gender development broadly and provides limited direct evidence about transgender identity.

Sex Beyond the Genitalia: The Human Brain Mosaic

Methodology

• •
  The authors analyzed magnetic-resonance imaging datasets containing more than 1,400 brains.
• •
  They identified features showing the largest average sex differences and tested whether individual brains consistently contained male-typical or female-typical features.
• •
  They applied a related analysis to behavioral datasets containing more than 5,500 people.

Findings

• •
  Most brains contained a mixture of features that appeared more often in males, more often in females, or commonly in both groups.
• •
  Fully internally consistent male-typical or female-typical profiles were uncommon under the authors’ method.
• •
  Average group differences can coexist with extensive overlap and within-person variation.

Limitations

• •
  Critics showed that multivariate models can classify sex from structural brain patterns at rates above chance. The disagreement concerns whether accurate classification establishes two internally consistent brain types.
• •
  The study examined sex-related brain features. It did not test transgender identity directly.

Structural, Functional, and Metabolic Brain Differences as a Function of Gender Identity or Sexual Orientation

Methodology

• •
  The authors systematically reviewed human neuroimaging literature through 2018 and discussed later studies published through March 2021.
• •
  The review included 39 studies concerning gender identity and 24 concerning sexual orientation.

Findings

• •
  Some structural and functional features among transgender participants resembled patterns associated with their gender identity.
• •
  Many features remained closer to patterns associated with sex assigned at birth, and other findings appeared intermediate or distinct.
• •
  The literature did not reveal a single reliable neuroanatomical marker of transgender identity.

Limitations

• •
  Many studies used small samples and different imaging methods.
• •
  Hormone exposure, age, sexual orientation, scanner differences, and analytic choices complicated comparisons.
• •
  Cross-sectional findings cannot establish whether a difference preceded gender incongruence or developed through later experience.

The Neuroanatomy of Transgender Identity: Mega-Analytic Findings From the ENIGMA Transgender Persons Working Group

Methodology

• •
  The researchers pooled data from eight sites and analyzed 803 participants.
• •
  The sample included 214 transgender men, 172 transgender women, 221 cisgender men, and 196 cisgender women who had not received gender-affirming hormones.
• •
  The study compared cortical thickness, surface area, and subcortical volume while correcting for multiple comparisons.

Findings

• •
  The analysis found no significant group differences in cortical thickness after correction.
• •
  Differences in surface area and subcortical volume did not amount to a simple shift from one cisgender group toward the other.
• •
  The authors described the results as a distinct neuroanatomical pattern rather than a complete masculinization or feminization of the brain.

Limitations

• •
  The study was cross-sectional and cannot establish cause or developmental timing.
• •
  Pooling data across scanners and sites adds heterogeneity.
• •
  Group averages cannot identify an individual’s gender.

A Sex Difference in the Human Brain and Its Relation to Transsexuality

Methodology

• •
  The authors measured the central subdivision of the bed nucleus of the stria terminalis in postmortem brain tissue.
• •
  They compared a small number of transgender women with male and female reference groups.

Findings

• •
  The measured region in the transgender women fell within the female-typical range reported by the study.
• •
  The authors reported that the finding did not track sexual orientation in their comparison cases.

Limitations

• •
  The transgender sample was extremely small.
• •
  Most transgender participants had received long-term hormone therapy.
• •
  Adult postmortem data cannot establish whether the difference caused, followed, or merely correlated with gender identity.

Sex Reassignment at Birth: Long-Term Review and Clinical Implications

Methodology

• •
  The authors followed an XY child whose penis had been destroyed during infancy and who was then surgically reassigned and raised as a girl.
• •
  They interviewed the patient, his family, and clinicians about development and later identity.

Findings

• •
  Reimer rejected the female sex of rearing and began living as male during adolescence.
• •
  The outcome contradicted earlier reports that described the reassignment as successful.
• •
  The case undermined the claim that rearing alone can reliably determine gender identity.

Limitations

• •
  One unusual clinical case cannot determine the relative contribution of biology and environment across the population.
• •
  Reimer experienced major medical trauma, secrecy, repeated examinations, and family distress. Those factors limit broad causal claims.

SOCIAL & HISTORICAL DIMENSIONS OF GENDER

Standards of Care for the Health of Transgender and Gender Diverse People, Version 8

What the source establishes

• •
  Gender-diverse identities and social categories appear across cultures and languages.
• •
  Terms such as hijra, fa’afafine, travesti, muxe, and Two-Spirit have distinct cultural histories and do not translate cleanly into one English category.
• •
  Transgender and nonbinary function as broad contemporary terms, while culturally specific terms should retain their local meaning.

Limitations

• •
  WPATH provides clinical guidance and professional consensus. It does not supply a single anthropological history of every cultural group.
• •
  Examples from one culture should not be treated as interchangeable with identities from another culture.

United Nations Free & Equal: Celebrate Trans Visibility

What the source establishes

• •
  Gender diversity has deep historical and cultural roots in many societies.
• •
  Contemporary English vocabulary does not exhaust the ways societies organize gender.

Limitations

• •
  This is a human-rights educational source.
• •
  It provides examples rather than a systematic anthropological review.

CLINICAL CLASSIFICATION & PROFESSIONAL POSITIONS

American Psychiatric Association: Gender Dysphoria Diagnosis

What the source establishes

• •
  Gender nonconformity does not constitute a mental disorder by itself.
• •
  Gender dysphoria refers to clinically significant distress or impairment associated with gender incongruence.
• •
  A transgender person may experience gender dysphoria, although transgender identity does not automatically produce the diagnosis.

Limitations

• •
  Diagnostic manuals classify conditions for clinical use. They do not provide a complete theory of gender identity.
• •
  The diagnosis remains debated because it can help people access care while also carrying a history of pathologization.

World Health Organization: Gender Incongruence and Transgender Health in the ICD

What the source establishes

• •
  ICD-11 replaced older categories such as “transsexualism” and “gender identity disorder of children.”
• •
  WHO moved gender incongruence out of the chapter on mental and behavioral disorders.
• •
  ICD-11 places gender incongruence in the chapter on conditions related to sexual health so health systems can continue to code relevant care.

Limitations

• •
  Classification reflects clinical utility and expert review. It does not turn every policy position about trans people into a medical conclusion.

American Psychological Association Resolution on Gender Identity Change Efforts

What the source establishes

• •
  APA opposes portrayals of transgender and nonbinary people as mentally ill because of their identities or expressions.
• •
  APA states that gender-identity change efforts lack adequate scientific support and carry a risk of harm.

Limitations

• •
  This is an organizational policy resolution rather than an original experiment.
• •
  A professional resolution establishes the association’s position. It does not eliminate the need to inspect the cited evidence for a specific empirical claim.

TRANS PEOPLE IN SPORTS

Sport and Transgender People: A Systematic Review of the Literature Relating to Sport Participation and Competitive Sport Policies

Methodology

• •
  The authors reviewed eight empirical studies and 31 competitive-sport policies.
• •
  The evidence included studies of hormone-related physiology and a small amount of direct performance data.

Findings

• •
  The review found no direct and consistent evidence of an overall competitive advantage across the sparse literature available at the time.
• •
  The authors found that many policies lacked a clear evidentiary basis and varied substantially across organizations.

Limitations

• •
  Only eight empirical studies met the criteria, and very few studied trained or elite athletes.
• •
  The conclusion reflects insufficient direct evidence in 2017. It cannot establish that no performance differences exist.
• •
  Later studies provide additional information about strength, lean mass, hemoglobin, and running performance.

Effect of Gender-Affirming Hormones on Athletic Performance in Transwomen and Transmen

Methodology

• •
  The researchers analyzed annual fitness-test records before and after the start of gender-affirming hormone therapy.
• •
  Tests included push-ups, sit-ups, and a 1.5-mile run.
• •
  The cohort included military personnel rather than elite athletes.

Findings

• •
  Before hormone therapy, trans women completed 31% more push-ups and 15% more sit-ups and ran 21% faster than cisgender women in the comparison group.
• •
  After two years of feminizing hormone therapy, push-up and sit-up differences were no longer statistically significant.
• •
  Trans women still ran about 12% faster on average after two years in this cohort.
• •
  Trans men reached or exceeded the cisgender male average for several tests after testosterone therapy.

Limitations

• •
  The study used military fitness data, which do not measure elite sport performance.
• •
  Training history, adherence, and other confounders remained outside the researchers’ control.
• •
  Average group differences do not determine the outcome of a particular athlete or event.

How Does Hormone Transition in Transgender Women Change Body Composition, Muscle Strength and Haemoglobin?

Methodology

• •
  The authors reviewed studies of transgender women receiving feminizing hormone therapy.
• •
  They focused on lean body mass, muscle area, strength, and hemoglobin because these traits can affect athletic performance.

Findings

• •
  Hemoglobin generally moved into the cisgender female range after several months of hormone therapy.
• •
  Lean body mass, muscle area, and strength declined during treatment.
• •
  Some differences in strength and lean mass could remain after 12 to 36 months.

Limitations

• •
  Most participants were not athletes.
• •
  The studies measured physiological proxies more often than performance in a specific sport.
• •
  Study size, treatment duration, and methods varied substantially.

Strength, Power and Aerobic Capacity of Transgender Athletes: A Cross-Sectional Study

Methodology

• •
  The researchers tested 19 cisgender men, 12 transgender men, 23 transgender women, and 21 cisgender women who participated in competitive sports or structured training.
• •
  Tests included body composition, grip strength, jump performance, lung function, and maximal oxygen uptake.

Findings

• •
  Trans women had higher absolute grip strength than cisgender women in this sample.
• •
  Trans women had lower jump height relative to fat-free mass and lower maximal oxygen uptake relative to body weight than cisgender women.
• •
  Absolute maximal oxygen uptake did not differ significantly between trans women and cisgender women.
• •
  Results varied by metric, which supports direct study of sport-relevant performance rather than a single proxy.

Limitations

• •
  The study was cross-sectional and cannot show how an individual changed during hormone therapy.
• •
  The groups were small and differed in age, height, weight, sport, and training history.
• •
  Laboratory measures do not directly predict medals, rankings, or injury risk in every sport.

Current policy note

BATHROOMS, SAFETY & PUBLIC ACCOMMODATIONS

Gender Identity Nondiscrimination Laws in Public Accommodations: Evidence Regarding Safety and Privacy

Methodology

• •
  The authors matched Massachusetts localities with gender-identity-inclusive public-accommodation ordinances to localities without comparable ordinances.
• •
  They obtained police incident reports involving assault, sex crimes, and voyeurism in restrooms, locker rooms, and changing rooms.
• •
  They compared incident patterns before and after the policies took effect.

Findings

• •
  Inclusive ordinances were not associated with an increase in the number or frequency of reported safety and privacy incidents.
• •
  Reported incidents in these facilities were rare in both sets of localities.

Limitations

• •
  The study covers Massachusetts and may not capture every local context.
• •
  Police reports omit incidents that victims never report.
• •
  The rarity of recorded incidents limits the ability to detect very small changes.

2022 U.S. Trans Survey: Public Life

Methodology

• •
  The survey collected online responses from 92,329 transgender people age 16 or older in the United States and its territories.
• •
  The project used community outreach and received institutional review board approval from UCLA.

Findings

• •
  Four percent of respondents reported being denied restroom access during the previous year.
• •
  Six percent reported verbal harassment, physical attack, or unwanted sexual contact while accessing or using a restroom during the previous year.

Limitations

• •
  The survey used a large nonprobability sample, so it cannot provide a nationally representative prevalence estimate.
• •
  Self-selection and recall can affect the results.
• •
  The survey documents respondents’ experiences. It does not test the effect of a specific law.

LANGUAGE, PRONOUNS & SINGULAR THEY

Oxford English Dictionary: A Brief History of Singular They

What the source establishes

• •
  English speakers have used “they” with a singular antecedent for more than six centuries.
• •
  The older use commonly referred to an unknown, indefinite, or generic person.
• •
  The pronoun’s contemporary use for a known nonbinary person extends an established singular pattern.

Limitations

• •
  Historical use of indefinite singular “they” does not mean every earlier writer used it as a nonbinary identity pronoun.
• •
  Grammar history establishes linguistic legitimacy. It does not settle broader political disagreements about gender.

APA Style: Singular They

What the source establishes

• •
  APA Style accepts singular “they” for an unknown or generic person.
• •
  APA Style accepts singular “they” for a known person who uses that pronoun.
• •
  Standard agreement remains plural in form, as in “they are.”

Limitations

• •
  A style guide sets a writing standard. It does not serve as an empirical study of mental-health outcomes or social policy.

SOCIAL TRANSITION & TRANS YOUTH

Gender Identity 5 Years After Social Transition

Methodology

• •
  The researchers followed 317 children who had socially transitioned between ages 3 and 12.
• •
  The children entered the study at an average age of 8 and received repeated follow-up over about five years.
• •
  The study recorded whether participants identified as transgender, nonbinary, or cisgender at follow-up.

Findings

• •
  At the end of the study period, 94% identified as binary transgender.
• •
  About 3.5% identified as nonbinary.
• •
  About 2.5% identified as cisgender.
• •
  Later retransition occurred more often among children who had socially transitioned before age 6 than among those who transitioned at age 6 or older.

Limitations

• •
  The sample included children with supportive families who had already completed a social transition.
• •
  Most participants were White and came from families with relatively high incomes.
• •
  The study describes identity trajectories in this cohort. It cannot determine the outcome for every gender-questioning child.
• •
  Five years does not provide lifetime follow-up.

Mental Health and Self-Worth in Socially Transitioned Transgender Youth

Methodology

• •
  The researchers compared socially transitioned transgender children with age-matched and gender-matched cisgender controls and with siblings.
• •
  Children and parents completed standardized measures of depression, anxiety, and self-worth.

Findings

• •
  Transgender participants showed depression and self-worth scores comparable to the control groups.
• •
  Anxiety was slightly higher among transgender participants, although it remained below levels reported in many earlier clinical samples.

Limitations

• •
  The study was cross-sectional and lacked mental-health measurements from before social transition.
• •
  Families volunteered for a research project and generally supported their children.
• •
  The results establish an association in this sample and cannot prove that social transition caused the observed mental-health profile.

DISCRIMINATION, VICTIMIZATION & MINORITY STRESS

A Systematic Review of Social Stress and Mental Health Among Transgender and Gender-Nonconforming People in the United States

Methodology

• •
  The authors reviewed U.S. research on stigma, discrimination, victimization, rejection, concealment, and mental health among transgender and gender-nonconforming people.
• •
  They organized the evidence using minority-stress theory.

Findings

• •
  Studies consistently associated discrimination, rejection, and victimization with depression, anxiety, substance use, suicidal thoughts, and suicide attempts.
• •
  Social support, identity pride, and community connection appeared as protective factors in portions of the literature.
• •
  The review located mental-health disparities within chronic social stressors rather than treating transgender identity as an inherent pathology.

Limitations

• •
  Most included studies were cross-sectional and used convenience samples.
• •
  Measures and terminology varied across studies.
• •
  Associations between stress and mental health can run in more than one direction, although longitudinal and daily-diary research strengthens the minority-stress explanation.

Gender Identity Disparities in Criminal Victimization: National Crime Victimization Survey, 2017–2018

Methodology

• •
  The researchers pooled 2017 and 2018 NCVS data for people age 16 and older.
• •
  They compared violent and property victimization rates for transgender and cisgender respondents.

Findings

• •
  Transgender respondents experienced 86.2 violent victimizations per 1,000 people, compared with 21.7 per 1,000 cisgender people.
• •
  The estimated rate was about four times higher for transgender people.
• •
  About half of violent victimizations were not reported to police in both populations.

Limitations

• •
  The number of transgender respondents was much smaller than the number of cisgender respondents, which widens uncertainty for subgroup estimates.
• •
  The data combine two years and do not establish the cause of each disparity.
• •
  Survey wording and disclosure can affect identification of transgender respondents.

2022 U.S. Trans Survey: Safety

Findings

• •
  Thirty percent of respondents reported verbal harassment during the previous year because of gender identity or expression.
• •
  Three percent reported a physical attack during the previous year for the same reason.
• •
  Nine percent reported denial of equal treatment or service.
• •
  Seventy-three percent reported some level of discomfort asking police for help, including 47% who felt very uncomfortable.

Limitations

• •
  The sample is large and diverse but not nationally representative.
• •
  The survey relies on self-report and cannot independently verify every incident.
• •
  Advocacy organizations conducted the survey with an academic advisory structure and UCLA institutional review board approval. Readers should consider both the methodology and the sponsoring organizations.

2022 U.S. Trans Survey: Health and Wellbeing

Findings

• •
  Respondents with supportive families reported lower lifetime suicidal thoughts than respondents with unsupportive families, 78% compared with 88%.
• •
  Past-year suicidal thoughts rose from 31% among respondents reporting no discrimination or harassment to 50% among those verbally harassed and 63% among those physically assaulted.
• •
  Respondents who had socially or medically transitioned reported higher happiness, thriving, and life satisfaction than respondents who had not.

Limitations

• •
  Cross-sectional comparisons cannot establish causation.
• •
  The survey did not use a probability sample.
• •
  Differences between groups can reflect age, access to care, income, family support, and other factors that require statistical analysis beyond raw percentages.

RELIGIOUS & PHILOSOPHICAL ARGUMENTS

Eunuchs in the Bible

Galatians 3:28

Selective use of biblical law

Personal identity

STUDIES TO WATCH OUT FOR

Rapid Onset Gender Dysphoria: Parent Reports on 1,655 Possible Cases

Retraction notice

Claim commonly attached to the study

What the study did

• •
  The authors analyzed reports submitted by parents who contacted ParentsofROGDKids.com because they believed their children had rapid-onset gender dysphoria.
• •
  The study included no interviews with the young people and no independent clinical assessments.

Problems

• •
  The journal retracted the article because survey participants had not provided written informed consent to participate in scholarly research or to have their responses published.
• •
  Recruitment selected parents who already accepted the study’s central explanation.
• •
  Parent reports cannot establish the internal experience, diagnosis, or causal history of the young person.

Bottom line

Parent Reports of Adolescents and Young Adults Perceived to Show Signs of Rapid-Onset Gender Dysphoria

Original article and correction

Claim commonly attached to the study

Methodology

• •
  The study surveyed 256 parents recruited from 4thWaveNow, Transgender Trend, and Youth Trans Critical Professionals.
• •
  The recruitment sites hosted parents and professionals skeptical of youth transition.
• •
  The study did not survey the adolescents, young adults, clinicians, or neutral third parties.

What the correction says

• •
  Rapid-onset gender dysphoria is not a formal mental-health diagnosis.
• •
  The study did not validate the proposed phenomenon.
• •
  The data generate hypotheses from parent observations and require research that includes young people and clinicians.

Bottom line

Reduction in Mental Health Treatment Utilization After Gender-Affirming Surgeries

Claim commonly attached to the study

Methodology

• •
  The study identified 2,679 people diagnosed with gender incongruence in Swedish national registers from 2005 through 2015.
• •
  The authors examined mental-health treatment during 2015 in relation to time since hormone therapy or surgery.

Findings and correction

• •
  The original analysis associated more time since surgery with lower use of mental-health treatment.
• •
  Additional comparisons between people who had and had not received surgery did not show a statistically significant advantage for surgery on the measured 2015 outcomes.
• •
  The study was observational and did not randomly assign treatment.

Bottom line

Brain Maturation, Cognition and Voice Pattern During Pubertal Suppression

Full article

Claim commonly attached to the study

Methodology

• •
  The researchers followed one transgender adolescent receiving a GnRH analogue.
• •
  They collected MRI, voice, and cognitive measurements before treatment and after 22 and 28 months.

Problems

• •
  A one-person report has no untreated comparison group.
• •
  Repeated cognitive scores can vary because of measurement error, mental health, medication, sleep, learning conditions, and other clinical factors.
• •
  The design cannot attribute a score change to the medication.

Bottom line

Cognitive Functioning of Girls Treated With GnRH Analogues for Precocious Puberty

Cognitive, Emotional, and Psychosocial Functioning of Girls Treated With Pharmacological Puberty Blockage

Claim commonly attached to the study

Methodology

• •
  The researchers compared 15 girls treated with GnRH analogues for idiopathic central precocious puberty with 15 age-matched controls.
• •
  They assessed cognitive, emotional, behavioral, and social functioning.

Findings

• •
  The treated and control groups did not differ significantly in general cognitive functioning, behavior, or social problems.
• •
  Measures of emotional processing produced differences that the authors considered uncertain and in need of further study.

Limitations

• •
  The sample was small.
• •
  Participants were cisgender girls treated for precocious puberty, which differs in age, indication, and clinical context from treatment for gender dysphoria.

Bottom line

Association Between Pretreatment IQ and Educational Achievement After Puberty Suppression

Full article information

Methodology

• •
  The researchers measured pretreatment IQ in 72 transgender adolescents at an average age of 12.78.
• •
  They measured educational achievement after gender-affirming treatment at an average age of 20.40.

Findings

• •
  Pretreatment IQ strongly predicted later educational achievement.
• •
  The relationship resembled the relationship observed in the general population.

Limitations

• •
  The study did not repeat a complete IQ test before and after puberty suppression.
• •
  Educational attainment provides an indirect measure of cognitive development.
• •
  The sample came from one specialized Dutch program.

Bottom line

SEX EDUCATION

Abstinence-Only and Comprehensive Sex Education and the Initiation of Sexual Activity and Teen Pregnancy

PubMed record

Methodology

• •
  The researchers analyzed 1,719 never-married heterosexual adolescents ages 15 to 19 from the 2002 National Survey of Family Growth.
• •
  They compared reported outcomes among adolescents who received comprehensive sex education, abstinence-only education, or no formal sex education before first intercourse.
• •
  The analysis adjusted for measured demographic and behavioral differences.

Findings

• •
  Comprehensive sex education was associated with lower odds of reported teen pregnancy compared with no formal sex education, adjusted odds ratio 0.40.
• •
  Abstinence-only education showed no statistically significant association with teen pregnancy or initiation of vaginal intercourse.
• •
  Teaching contraception was not associated with an increased likelihood of sexual activity.

Limitations

• •
  The study was observational and relied on retrospective self-report.
• •
  Curricula varied within the broad categories.
• •
  Unmeasured family, school, and community factors could affect the results.

Abstinence-Only Education and Teen Pregnancy Rates

Full article

Methodology

• •
  The authors compared abstinence emphasis in state laws and policies with teen pregnancy and birth rates across 48 states.
• •
  They adjusted for several state-level factors, including income, educational attainment, racial composition, and Medicaid family-planning waivers.

Findings

• •
  Greater abstinence emphasis correlated with higher teen pregnancy and birth rates.
• •
  The association remained after the authors adjusted for the measured state-level variables.

Limitations

• •
  This ecological analysis uses states rather than individual students as the unit of analysis.
• •
  Correlation cannot establish that the curriculum caused the state-level outcome.
• •
  States differ in many political, religious, economic, and healthcare factors that the model may not fully capture.

ACOG Committee Opinion on Comprehensive Sexuality Education

American College of Obstetricians and Gynecologists guidance

What the source establishes

• •
  ACOG states that abstinence-only programs have not shown effectiveness in delaying sexual activity or reducing adolescent pregnancy.
• •
  ACOG recommends instruction that develops knowledge and practical skills across childhood and adolescence.

Limitations

• •
  This is a professional policy statement based on a body of evidence.
• •
  Specific curricula still require direct evaluation for implementation quality and outcomes.

LGBTQ-INCLUSIVE EDUCATION

LGBTQ-Inclusive Curricula: Why Supportive Curricula Matter

Study PDF

Methodology

• •
  The authors analyzed survey data from 1,232 LGBTQ and heterosexual students in 154 California middle and high schools.
• •
  They used multilevel models to examine the relationship between inclusive curricula, school safety, and bullying.

Findings

• •
  Students in schools with more supportive LGBTQ-inclusive content reported greater safety.
• •
  Inclusive curricula were associated with lower school-level bullying.
• •
  The supportiveness and quality of the material mattered more than a simple mention of LGBTQ people.

Limitations

• •
  The study used cross-sectional data from California in 2008.
• •
  Students were not randomly assigned to curricula.
• •
  School climate may influence both curriculum choices and student outcomes.

GLSEN 2017 National School Climate Survey

Survey report

Findings

• •
  Seventy percent reported verbal harassment based on sexual orientation during the previous school year.
• •
  Students with LGBTQ-inclusive curricula reported lower levels of feeling unsafe because of sexual orientation than students without inclusive curricula, 41.8% compared with 63.3%.
• •
  Supportive staff, inclusive curricula, and enumerated anti-bullying policies were associated with better school experiences.

Limitations

• •
  GLSEN used a large nonprobability sample recruited partly through LGBTQ networks.
• •
  The survey relied on self-report.
• •
  Cross-sectional associations cannot prove that curriculum alone caused the difference.

PUBLIC OPINION

LGBTQ+ Identification Holds at 9% in the United States

Gallup, 2026

Methodology

• •
  Gallup aggregates national telephone interviews conducted throughout the year.
• •
  Respondents may select more than one LGBTQ identity, while the overall LGBTQ figure counts each person once.

Findings

• •
  LGBTQ identification remained near the record level measured in 2024.
• •
  Gallup estimated that between 1% and 2% of U.S. adults identified as transgender.
• •
  Younger adults reported LGBTQ identities at much higher rates than older adults, with bisexual identity accounting for most of the generational difference.

Limitations

• •
  Identity estimates depend on survey wording, disclosure, age coverage, and sampling.
• •
  LGBTQ combines sexual orientation and gender identity, so the total should not be described as a transgender prevalence estimate.

Two-Thirds in the United States Prefer Birth Sex on IDs and in Athletics

Gallup, 2025

Findings

• •
  Sixty-nine percent said transgender athletes should participate on teams matching sex assigned at birth.
• •
  Sixty-six percent said government documents should list sex assigned at birth rather than current gender identity.
• •
  Views differed sharply by party, and support for participation based on current gender identity had declined from Gallup’s 2021 measurement.

Limitations

• •
  The wording presents a forced choice and does not measure views on sport-specific rules, transition status, age, or different types of identification documents.
• •
  Public opinion measures political preference. It does not determine the empirical effect of a policy.

Americans’ Complex Views on Gender Identity and Transgender Issues

Pew Research Center, 2022

Findings

• •
  Sixty-four percent favored laws protecting transgender people from discrimination in jobs, housing, and public spaces.
• •
  Fifty-eight percent favored requiring transgender athletes to compete based on sex assigned at birth.
• •
  Forty-one percent favored requiring restroom use based on sex assigned at birth, while 31% opposed that requirement.
• •
  Majorities recognized that transgender people face at least some discrimination.

Limitations

• •
  The results capture opinion in 2022 and should be dated when quoted.
• •
  Responses change with question wording and the amount of policy detail supplied.
• •
  Political opinion cannot verify biological, medical, or safety claims.

KEY STATS & QUICK CITATIONS

• •
  Sex measurement: The National Academies describes sex as a multidimensional cluster of anatomical and physiological traits and recommends measuring the trait relevant to the research or clinical purpose.
• •
  Intersex prevalence: About 1.7% under the broad Blackless definition; about 0.018% under Sax’s narrow definition. State the definition whenever using either number.
• •
  Social transition follow-up: In Olson’s cohort of 317 children, 94% identified as binary transgender, 3.5% as nonbinary, and 2.5% as cisgender after about five years.
• •
  Bathroom laws: The Massachusetts matched-locality study found no increase in reported safety or privacy incidents after adoption of trans-inclusive public-accommodation ordinances.
• •
  Violent victimization: The 2017–2018 NCVS analysis estimated 86.2 violent victimizations per 1,000 transgender people and 21.7 per 1,000 cisgender people.
• •
  Singular they: The Oxford English Dictionary traces singular use to about 1375.
• •
  Sports: Hormone therapy lowers several performance-related measures, while the size and duration of remaining differences vary by measure. Current evidence supports sport-specific analysis.
• •
  Public opinion: Gallup reported 9.0% LGBTQ identification among U.S. adults in 2025 and between 1% and 2% identifying as transgender.