John Money was a prominent 20th-century psychologist and sexologist affiliated with Johns Hopkins University. He became highly influential in the study of human sexual behavior and gender development, pioneering terms like “gender role” and popularizing the distinction between biological sex and social gender. The “John Money Experiment” refers to a highly controversial case study intended to prove that gender identity is primarily shaped by environment and upbringing rather than biology. This case became a devastating test of the nature versus nurture debate in human psychosexual development.
The Theory of Gender Neutrality
Money’s research was underpinned by the “blank slate” theory concerning gender identity. This theory proposed that a child is born psychosexually neutral and that their sense of being male or female is primarily imprinted through social learning and upbringing. He asserted that biological factors were not the sole determinants of core gender identity.
A central part of this framework was the “critical period hypothesis,” suggesting that gender identity becomes fixed during early childhood. Money believed that if consistent rearing occurred before the child reached approximately 18 to 24 months of age, the assigned gender identity would successfully take hold. This hypothesis led Money to advocate for surgical and hormonal interventions for infants with ambiguous genitalia, ensuring they were raised in an unambiguous sex to prevent psychosocial harm. He generalized this theory, claiming that environment and rearing were the overriding factors for all children.
The Case Study and Intervention
The opportunity to test this theory on a biologically unambiguous male arose following a tragic medical accident in 1966. A seven-month-old identical twin boy suffered an irreparable injury to his penis during a routine circumcision using an electrical cauterization device. The distraught parents were referred to Dr. Money, who presented a radical solution based on his theory of gender malleability.
Money advised the parents to proceed with a complete sex reassignment, including surgical castration and reconstruction of female-like genitalia. The boy was renamed and socially reared as a girl, with the expectation that estrogen therapy would be administered at puberty to foster secondary female characteristics. Money used the boy’s genetically identical twin brother as a control subject to measure the success of the environmental manipulation.
Money documented the case as the “John/Joan case” to protect anonymity. He publicly reported the intervention as a resounding success, claiming the child exhibited typical female behaviors and gender identity. This assertion was presented to the scientific community as evidence that a male could be successfully “transformed” into a female if interventions occurred within the critical period. The apparent success reinforced Money’s influence and solidified his protocols for treating infants with atypical sex anatomies.
The Outcome and Public Disclosure
Despite Money’s public claims, the subject, known as Brenda, exhibited profound distress and rejected the assigned female role from an early age. The child resisted conforming to feminine stereotypes and displayed consistent masculine behaviors, preferring to play with boys and rejecting dolls and dresses. This psychological misalignment created a deeply troubled childhood, marked by social isolation and confusion.
By adolescence, the psychological burden became overwhelming, and the parents disclosed the true story of the botched circumcision and reassignment. Upon learning the truth, the individual immediately rejected the female identity and began living as a male, adopting the name David Reimer. The experiment’s failure was first exposed by sexologist Milton Diamond, who argued for the strong role of prenatal biological factors in gender identity.
The full, tragic details of David Reimer’s life were widely publicized in 2000 through the work of journalist John Colapinto. The public learned of the psychological damage caused by the experiment and the deception used to maintain the facade of success. Reimer’s life was marked by ongoing mental health struggles, compounded by personal tragedies, including the suicide of his twin brother in 2002. David Reimer ultimately took his own life in 2004, at the age of 38, concluding the case that had promoted the theory of gender neutrality.
Enduring Ethical and Scientific Legacy
The true outcome of the John Money experiment fundamentally shifted modern scientific understanding regarding the origins of gender identity. The case served as evidence against the pure “blank slate” model, demonstrating that biology imposes constraints on the malleability of gender identity, even with intensive social and medical intervention. This failure moved the scientific consensus toward recognizing that prenatal biological factors, such as hormonal exposure, play a significant role in psychosexual development.
The case also initiated a widespread re-evaluation of medical ethics, particularly concerning informed consent and research integrity involving vulnerable subjects. Money’s deceptive reporting and the suffering inflicted highlighted the power imbalance between the researcher and the desperate family. The experiment’s legacy led to significant changes in the clinical management of intersex infants, promoting a shift away from automatic, early-life genital surgeries toward an approach prioritizing long-term psychological well-being and patient autonomy.