As for what causes transsexuality, no one can say for certain-just as no one can say for sure what causes homosexuality. Scientists who hold the view that gender identification is innate believe that transsexuals either have abnormal genes or have brains that have been exposed to hormonal abnormalities in the womb.
主張性別天生的學者認為，變性慾者在母親肚子裡時，因為大腦中的性別中樞受到錯誤荷爾蒙影響，或是遺傳基因的位置錯誤所導致。