1. Sex Drive  The Hypothalamus mediates sex drive in animals. The areas are different for males versus females.  Males: medial preoptic area  Females: ventomedial area

2. Hormonal Effects After Puperty For Males: Testosterone is needed to maintain sex drive. 1) Castration reduces sex drive 2) Injection of testosterone restores it

3. Hormonal Effects After Puberty For female nonhuman animals: Estrogen and progesterone maintain sex drive. For human females: Estrogen and progesterone are not needed. Testosterone (produced by the adrenals) maintains sex drive.

4. Some studies indicate a 3% to 7% chance of a male being gay If a brother is gay then the chance can be as high as 25% Different studies have different estimates of the frequency of homosexuality

8. 66% of mothers of male homosexuals recall stress during pregnancy 33% for bisexuals 10% for heterosexuals

9. The incidence of male homosexuality is more than double that of female homosexuality

10. Marind Anim of New Guinea  at age 6 the father chooses an adult male  from 12 to 16 adolescent has several male lovers  opposite sex marriages are arranged

11. Batak of Northern Sumatratra  children view as sexual at age 6  6-16 years of age same sex activity is encouraged  adolescents best friend describes sexual prowess of his mate to convince girl and his parents that he would be a good mate

12. A Linkage Between DNA Markers on the X Chromosome and Male Sexual Orientation