Sexual orientation


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  • It’s easy to spot a gay or lesbian in a crowd. : stereotypes apply to some not all: gay match making show Lesbians and gays are always trying to seduce heterosexuals.: gays interested in other gays. Also, straight people far more likely to seduce children. Gays and lesbians are oversexed.: gays have similar sex drive as straights - gay men have more partners than straight men (female limited - not lack of interest on straight male part) Bisexual have the best of both worlds.: no - they are often ostracised from both groups - have to hide straight side from gay friends, vice versa. Within a relationship setting, gays and lesbians mimic traditional heterosexual patterns.: male role and female role - this happens in some cases, but typically the exception see study following...
  • Discuss the fact that many gay men do not like feminine males - “if I wanted to have sex with a woman, I’d be straight.”
  • After this slide, show video clip
  • Question: rates of psychopathology are higher among gays and lesbians. Why? Would you predict rates of these problems to be lower in gay friendly communities?
  • note 48% not concordant
  • Xq28 region: examined brothers concordant for homosexuality, Xq28 region similar for 33/40 pairs of brothers - this region codes for dozens to hundreds of genes
  • INAH2 and 3 regions larger in men than women Homosexual men died of AIDS area INAH3 differentiated groups: larger in straight men, similar in size between gay and straight women. Heterosexual men with and without AIDS did not differ INAH function unknown - but rich in androgen and estrogen receptors
  • Prenatal exogenous hormone administration: DES (synthetic estrogen) -> female offspring more likely to be lesbian maternal stress - 2nd trimester critical testosterone - high levels ass. Male and female gay handedness - mixed and left handedness associated with gay - may be related to prenatal testosterone OAEs - higher in hetero females than heteromales -bi and lesbian women intermediate -gay males hypermasculinized -opposite sex twins intermediate -related to prenatal androgens finger lengths, 2d:4d - ratio smaller in males than females, smaller in lesbians and gay men - related to prenatal T Testosterone levels in adults lower in gay men - related to stress higher in butch lesbians
  • Latter born sons more likely to be gay - each additional brother increases odds by 33% reflects the progressive immunization of some mothers to Y-linked minor histocompatibility antigen s ( H-Y antigen s) anti- H-Y antibodies produced by the mother pass through the placental barrier to the fetus and affect aspects of sexual differentiation in the fetal brain doesn’t happen with older sisters. Latter born sons with older brothers weigh less
  • balanced polymorphism -greater fertility in straight siblings - excess of feminine traights - women prefer men who are tender, sensitive, empathic - homosexuality may represent people who get too much of this trait biological exuberance- more diversity leads to greater stability and resilience reciprocal altruism - same sex alliances kin selection - reduces likelihood of nonproductive competition between earlier and latter born sons
  • Men rarely change - for gay men it appears to be hard wired. Some argue no such thing as a bisexual man - if given a choice, men will indicate a preference. Often men will have same sex relations because of circumstances (e.g., prison) or opposite sex relations because of circumstances (e.g., societal pressure. Show video clip from “straight - a conversion comedy” These women did not differ from those who maintained lesbian/bisexual identities regarding the age at which they underwent sexual identity milestones, the factors that precipitated their sexual questioning, or their recollection of childhood "indicators" same-sex sexuality.
  • Antisodomy laws recently struck down by the Supreme court - June 2003 - Lawrence vs. Texas
  • Antisodomy laws recently struck down by the Supreme court - June 2003 - Lawrence vs. Texas
  • Children have to contend with unique circumstances, but otherwise social and emotional development proceeds normally
  • 214/823
  • Gay marriage legal in Canada as of June 10, 2003 - currently pending in Canadian Supreme court
  • Sexual orientation

    1. 1. Sexual Orientation 1
    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. 2
    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) 3
    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 4
    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 5
    6. 6. Psychopathology(Fergusson et al., 1999) 6
    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). 7
    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) 8
    9. 9. Genetic Evidence• Sex - linked? – X-linked – Xq28 region• Some studies indicate homosexuality on both maternal and paternal sides (Bailey et al., 1999) 9
    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 10
    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 11
    12. 12. Birth Order• Latter born sons more likely to be gay• Mothers develop immunity to H-Y Antigen(Blanchard, 2001 ) 12
    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 13
    14. 14. Homosexuality & EvolutionHow can a trait that seems to inhibit thelikelihood of offspring remain in thepopulation? 14
    15. 15. Homosexuality & Evolution• balanced polymorphism• biological exuberance• reciprocal altruism - same sex alliances• kin-selection(Miller, 2000) 15
    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” 16
    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 17
    18. 18. Legal Issues• Antisodomy laws 18
    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) 19
    20. 20. Legal Issues• Antisodomy laws• Gay parents & gay adoption 20
    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 21
    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) 22
    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 23
    24. 24. Legal Issues• Antisodomy laws• Gay parents & gay adoption• Gay marriage 24