1. 1 Sexual Orientation

2. 2 Myth? Lesbians and gays are always trying to seduce heterosexuals. Gays and lesbians are oversexed. Bisexual have the best of both worlds. It’s easy to spot a gay or lesbian in a crowd. Within a relationship setting, gays and lesbians mimic traditional heterosexual patterns.

3. 3 Sex Typical Behavior Do gay men prefer feminine males? Lesbians prefer masculine females? –Both gay men and lesbians tend to prefer sex-typical appearance –preference less strong for feminine males –no typical preference for sex-typical behavior among lesbians (Bailey et al., 1997)

4. 4 Prevalence Alfred Kinsey (1953) –exclusively heterosexual 75-85% males 80-90% females –exclusively homosexual 4% males 2% females –bisexual 10-15% males 8-10% females More recent studies have replicated these rates

5. 5 Homosexuality as a Mental Illness DSM (1952): sociopathic personality disturbance DSM-R (1968): sexual deviation DSM-II (1973): ego-dystonic homosexuality –Criteria for mental disorders: causes personal distress interferes with social effectiveness DSM-III and beyond

6. 6 Psychopathology (Fergusson et al., 1999)

7. 7 Genetic Evidence Family studies –homosexual females more likely to have homosexual brothers (Bailey & Bell, 1993) –brothers concordant for homosexuality were similar in childhood gender nonconformity (Bailey, 2000) –gender nonconformity inherited trait for both males and females –90% of gay or bisexual males had sons who were straight (Bailey, 1995).

8. 8 Genetic Evidence Twin studies –52% concordance identical twins (male) –22% concordance fraternal twins (male) –11% concordance for genetically unrelated brothers (Bailey & Pillard, 1991)

9. 9 Genetic Evidence Sex - linked? –X-linked –Xq28 region Some studies indicate homosexuality on both maternal and paternal sides (Bailey et al., 1999)

10. 10 Brain Anatomy Evidence Hypothalamic differences: –suprachiasmatic nucleus (SCN) larger and has more cells in gay men (Swaab, 1990) –INAH1-4 regions (Simon LeVay, 1991) examined homosexual men, heterosexual men and women area INAH3 differentiated groups

11. 11 Hormone & Prenatal Evidence Prenatal –exogenous hormone administration DES –H-Y antigen –maternal stress –testosterone levels handedness otoacoustic emissions (OAEs) finger lengths, 2d:4d Testosterone levels in adulthood

12. 12 Birth Order Latter born sons more likely to be gay Mothers develop immunity to H-Y Antigen (Blanchard, 2001 )

13. 13 Behavioral Measures Gay men on average better at spatial rotation than gay women Gay men more aggressive and competitive than gay women Straight men more aggressive and competitive than gay men

14. 14 Homosexuality & Evolution How can a trait that seems to inhibit the likelihood of offspring remain in the population?

15. 15 Homosexuality & Evolution balanced polymorphism biological exuberance reciprocal altruism - same sex alliances kin-selection (Miller, 2000)

16. 16 Sex Differences in Sexual Orientation Is it a phase? –Men - hard wired –Lesbian and bisexual young women were followed over a 5 year period (Diamond, 2003) Over a quarter relinquished their gay identity –More likely to indicate attraction to both men and women –indicated that degree of attraction to men and women did not significantly Change –1 women described lesbian period as “a phase”

17. 17 Sex Differences in Sexual Orientation Sex differences in sexual arousal patterns (Chivers et al., in press) –examined gay and straight men and women, and male to female transsexuals –viewed male/male, female/female, and male/female erotica –gathered physiological and subjective data

18. 18 Legal Issues Antisodomy laws

19. 19 Antisodomy Laws Sec. 21.01. Definitions. (1) "Deviate sexual intercourse" means: (A) any contact between any part of the genitals of one person and the mouth or anus of another person; or (B) the penetration of the genitals or the anus of another person with an object. Sec. 21.06. Homosexual Conduct. (a) A person commits an offense if he engages in deviate sexual intercourse with another individual of the same sex. (b) An offense under this section is a Class C misdemeanor. ($500)

20. 20 Legal Issues Antisodomy laws Gay parents & gay adoption

21. 21 Gay Parents & Children of Gay Parents Comparing gay and straight parents (e.g., Allen & Burrell, 1996). –Parental data: parent’s rating of parent/child interaction parental attitude about sexual development rating of child’s level of satisfaction teacher’s rating of child’s school behavior –Child data: sexual orientation life satisfaction cognitive development

22. 22 Gay Parents & Children of Gay Parents Children of gay parents highly likely to report that their problems are related to their parent being gay (94%)(Cameron & Cameron, 2002) Children of gay parents equally likely to be teased, but teased about family (e.g., Vanfraussen et al., 2002)

23. 23 Gay Adoption Do adoption agencies allow gay adoption? –823 adoption agencies contacted, 26% responded (Brodzinsky et al., 2002) –of these: 63% accepted applications from gay couples 38% had made at least one gay adoption

24. 24 Legal Issues Antisodomy laws Gay parents & gay adoption Gay marriage