The hypothalamus is the sex center. Less than an ounce in weight and about the size of a cherry, it is larger in the male brain than in the female brain or in the brains of homosexuals and transsexuals. (Pease, Barbara and Allan. Why Men Don’t Listen and Women Can’t Read Maps. p 183-200. NY: Broadway Books, 1998.)
Sexual drive centers on the hypothalamus, but like other urges, it radiates out to encompass a wide range of other brain areas in both the limbic area and the cortex. (Carter, Rita, Ed. Mapping the Mind. p 72. CA: University of California Press, 1998.)
Refer to Sexuality and the Brain for additional information.