Mantys Alt: Sexuality and Gender: Findings from the Biological, Psychological, and Social Sciences. The hypothesis that gender identity is an innate, fixed property of human beings that is independent of biological sex—that a person might be “a man trapped in a woman’s body” or “a woman trapped in a man’s body”—is not supported by scientific evidence. ● According to a recent estimate, about 0.6% of U.S. adults identify as a gender that does not correspond to their biological sex. ● Studies comparing the brain structures of transgender and non-transgender individuals have demonstrated weak correlations between brain structure and cross-gender identification. These correlations do not provide any evidence for a neurobiological basis for cross-gender identification.