This document discusses factors that influence sexual attraction and homosexuality. It notes that sexual attraction is influenced by pheromones, histocompatibility genes between mates, youthful appearance signaling fertility, and the shape of the female form. Homosexuality exists on a continuum according to the Kinsey scale from exclusively heterosexual to exclusively homosexual. Research has explored potential biological and genetic factors influencing homosexuality such as hypothalamus size, brain morphology, gene differences, and the influence of sex differentiation in fetal development which may be impacted by maternal hormones. Twin studies also provide some evidence for genetic influences.

1. SEXUAL ATTRACTION

4. SEXUAL ATTRACTION 1) PHEROMONES…..CHEMICAL MESSAGES 2) HISTOCOMPATIBILITY GENE DIFFERENCES BASED ON SIGNIFICANT DIFFERENCES IN MATE’S IMMUNOLOGICAL CHARACTERISTICS. THIS DECREASES INCEST AND RECESSIVE GENES. 3) SHAPE OF FEMALE ( HOURGLASS AND HIP/WAIST/BUST) 4) YOUTHFUL APPEARANCE: BLOND, FULL BREASTED, SMOOTH SKIN, SUBCONCIOUS SELECTS FOR FERTILITY AND HEALTH

5. HOMOSEXUALITY

7. KINSEY HETEROSEXUAL/HOMOSEXUAL SCALE

8. As Kinsey writes in Sexual Behavior in the Human Male (1948):“Males do not represent two discrete populations, heterosexual and homosexual. The world is not to be divided into sheep and goats…The living world is a continuum in each and every one of its aspects."

9. the authors add in Sexual Behavior of the Human Female (1953):“It is a characteristic of the human mind that tries to dichotomize in its classification of phenomena….Sexual behavior is either normal or abnormal, socially acceptable or unacceptable, heterosexual or homosexual; and many persons do not want to believe that there are gradations in these matters from one to the other extreme.”

10. Kinsey also reported:“While emphasizing the continuity of the gradations between exclusively heterosexual and exclusively homosexual histories, it has seemed desirable to develop some sort of classification which could be based on the relative amounts of heterosexual and homosexual experience or response in each history... An individual may be assigned a position on this scale, for each period in his life.... A seven-point scale comes nearer to showing the many gradations that actually exist.”

11. The scale ranges from 0, for those who would identify themselves as exclusively heterosexual with no experience with or desire for sexual activity with their same sex, to 6, for those who would identify themselves as exclusively homosexual with no experience with or desire for sexual activity with those of the opposite sex, and 1-5 for those who would identify themselves with varying levels of desire or sexual activity with either sex.

12. Is gayness genetic or environmental 1) inborn error or mutation 2) androgyny 3) childhood socialization 4)Biological structures ---brain morphology 5) genetic

13. Structural Differences Hypothalamus size variation ( the INAH-3 area)……larger in straight men? Gay men may lateralize less? Gene differences. Studies of monozygotic vs. dizygotic twins

14. Genetic twin studies Monozygotic twins have more similar DNA Twin studies compare mono and di. If we compare, gay tendency tends to be higher if a mono twin is gay than with a dizygotic twin Could be that the “X” chromosome and gene Xq28 is similar in many gay brothers

15. Influence of sexual differentiation 6-14 weeks of fetal development and due to the presence of the y chromosome…….sex changes develop and may be compromised or altered by maternal hormonal influence At puberty ( secondary characteristics) develop due to estrogen/testosterone levels