Gender dysphoria (GD), or gender identity disorder (GID), is the distress a person experiences as a result of the sex and gender they were assigned at birth. In this case, the assigned sex and gender do not match the person's gender identity, and the person is transgender.
Further studies failed to reproduce the original experiment's results. One of those studies found that both caged and "park" rats showed a decreased preference for morphine, suggesting a genetic difference.
但跨性別者的生理證據在哪裡?1990 年代中期,許多人研究了跨性別者死後的腦解剖結構,發現男性與女性的根本差異起始於情緒中心「杏仁核」,杏仁核會發送訊息到下視丘,也就是身體所需各式荷爾蒙的指揮中心。這個被稱為終核紋(bed nucleus of the stria terminalis,BNST)的中心區主要負責「性」與「焦慮」反應,平均而言,男性的尺寸是女性的兩倍。因此,跨性別女(外表擁有男性解剖學結構,但一輩子都擁有女性性別認同)腦中的 BNST 相對男性而言尺寸較小,反而跟擁有女性內外生殖器官的人相同。