By DR. KATHERINE O’HANLAN
The amicus brief from the Gay and Lesbian Medical Association that I contributed to relates to the Supreme Court that the last 30 years of research provides solid evidence that sexual orientation and gender identity are biologically conferred during the first 12 weeks of pregnancy, and are as innate as handedness, height or skin color.
During that critical first trimester, the fetus is exposed to proteins, sex hormones and enzymes that result in numerous traits that are different for men and women. These sexually dimorphic traits include anatomy and physiology, certain brain structures, some physical skills and some cognitive skills. Among these sexually dimorphic traits are sexual orientation (most prefer the opposite sex) and gender identity (most men and women identify with the gender of their genital anatomy).
However, nature never confers traits in a perfectly dichotomous fashion, and never is precisely black or white, but rather expresses as infinite shades of grey across a broad spectrum of grays, some very dark, some not so dark, some light, some very light. Likewise, almost no one is perfectly heterosexual or homosexual, purely male or female, but some blend of features that make them unique. More than 50 published research studies in the National Library of Medicine provide evidence that transgender people and homosexual men and women are born with traits that fall in the mid portion, or even closer to the opposite-gender end of that spectrum. They are born with the cognitive and physiologic skills, bone anatomy and brain circuitry that are slightly or substantially more like the skills, features, orientation and identity of the opposite sex.
Observations of more than 450 species of animals confirm that fleas, birds, reptiles and primates (that is us) demonstrate bisexual or homosexual behavior including recreational sex to orgasm in the presence of the opposite gender, and lifelong pairings. Experimental evidence long ago demonstrated that injecting hormones into pregnant rodents and guinea pigs could reverse their sexual partner preferences. While such experiments would never be performed on humans, observations of multiple human medical conditions confirm the link between early development and sexually dimorphic traits including orientation and identity.
For example, when a female baby is born with a congenital abnormality of the adrenal gland, a missing enzyme causes a buildup of male-like hormones (androgens) to accumulate in the baby’s blood. Most female infants with this condition will have boy-like bone structures and play patterns, up to half of the girls will later identify as lesbian, and a few as transgender males, especially if they have the extreme forms of adrenogenital syndrome. Furthermore, research shows that girls who had a boy co-twin in their mothers’ wombs have more male-like bone structure and play patterns, and are more likely to identify as lesbian later in life. This is because the baby girl’s brain received some of her co-twin’s male hormones through their shared amniotic fluid membrane.
For baby boys, any subtle decrease in the usual level of essential male chemicals during the first part of pregnancy can increase his chance of becoming a gay male or transsexual. Seventeen published research reports have concluded that boys with many older brothers are more likely to be gay than boys with fewer older brothers. Why? Because every pregnant mother receives proteins from her baby boy’s blood that her body perceives as foreign, causing her to develop blocking antibodies to neutralize and remove them. With each successive boy pregnancy, the mother makes more blocking antibodies, progressively reducing the level of essential male chemical exposure to each subsequent male child.
The enormous multidisciplinary body of scientific evidence confirming the biologic basis of sexual orientation and gender identity is the substance of our brief to the Supreme Court, and should also inform our national debate and policy decisions. While, admittedly, the data is drab and overly scientific, the evidence is solid. Like skin or hair color, sexual orientation and gender identity are unchangeable, innocent, historically misunderstood and deserving of accommodation in our public laws. Our Supreme Court justices need this scientific information.
Dr. Katherine O’Hanlan is a gynecologic oncologist and surgeon who is past president of the Gay and Lesbian Medical Association. She is based in Portola Valley, Calif.