the brai has been shownn to be bisexual in fish, in reptiles more recently and now in mice.ink this ability to have the both presentations of the male and female brain could be totally relevant to gender identity. charlie: let me turn to melissa and talk about defining gender identity and sexual orientation and gender behavior. melissa: i study the role of testosterone and human development. we studied genetic conditions that cause people to have either higher or lower levels of testosterone during prenatal development than would otherwise be the case. from those people, evidence suggests testosterone in human also influences gender development, including gender identity. to start, it is useful to put this into context to expand our understanding of the dimensions of gender related behavior. we have talked about anatomical sex and gender identity which is our sense of self as male or female or something else. also, people have sexual orientation and this is separate to gender identity. it refers to our erotic interest in male, females, both or neither. finally, there is a th