The most famous application of Diamond’s theories was his follow-up on the case of David Reimer .

: In 1997, Dr. Diamond published a long-term review revealing that Reimer never accepted his female upbringing. Despite intensive social conditioning, Reimer experienced severe gender dysphoria, eventually discovering the truth and transitioning back to living as a male in his teens.

This report explores the key academic and clinical contributions of Dr. Milton Diamond to the fields of sexology and gender identity, with a focus on his influential work on the biological basis of sexual identity and the "John/Joan" case.

Milton Diamond, a prominent sexologist at the University of Hawaii, is best known for his challenges to the "neutrality at birth" theory of gender. His research emphasized that sexual identity and gender roles are strongly influenced by biological and prenatal factors rather than being solely a product of social rearing.

: After a botched circumcision in 1966 left Bruce (David) Reimer without a penis, psychologist John Money recommended the child be raised as a girl (named "Joan") to prove that gender is a learned social construct.