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Sexual Orientation. 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.
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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.
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)
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
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
Psychopathology (Fergusson et al., 1999)
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).
Genetic Evidence • Twin studies • 52% concordance identical twins (male) • 22% concordance fraternal twins (male) • 11% concordance for genetically unrelated brothers (Bailey & Pillard, 1991)
Genetic Evidence • Sex - linked? • X-linked • Xq28 region • Some studies indicate homosexuality on both maternal and paternal sides (Bailey et al., 1999)
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
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
Birth Order • Latter born sons more likely to be gay • Mothers develop immunity to H-Y Antigen (Blanchard, 2001)
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
Homosexuality & Evolution How can a trait that seems to inhibit the likelihood of offspring remain in the population?
Homosexuality & Evolution • balanced polymorphism • biological exuberance • reciprocal altruism - same sex alliances • kin-selection (Miller, 2000)
Sex Differences inSexual 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”
Sex Differences inSexual 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
Legal Issues • Antisodomy laws
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)
Legal Issues • Antisodomy laws • Gay parents & gay adoption
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
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)
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
Legal Issues • Antisodomy laws • Gay parents & gay adoption • Gay marriage