Origins of Sexual Orientation
If our sexual orientation is indeed something we do not choose and seemingly cannot
change (most clearly so for males), then where do these preferences—heterosexual or
homosexual—come from? See if you can anticipate the consensus that has emerged
from hundreds of research studies by responding yes or no to the following questions:
1. Is homosexuality linked with problems in a child’s relationships with parents,
such as with a domineering mother and an ineffectual father, or a possessive
mother and a hostile father?
2. Does homosexuality involve a fear or hatred of people of the other gender, leading
individuals to direct their sexual desires toward members of their own sex?
3. Is sexual orientation linked with levels of sex hormones currently in the blood?
4. As children, were many homosexuals molested, seduced, or otherwise sexually
victimized by an adult homosexual?
The answer to all these questions appears to be no (Storms, 1983). In interviews
with nearly 1000 homosexuals and 500 heterosexuals, Kinsey Institute investigators
assessed nearly every imaginable psychological cause of homosexuality—parental relationships,
childhood sexual experiences, peer relationships, dating experiences (Bell
et al., 1981; Hammersmith, 1982). Their findings: Homosexuals are no more likely
than heterosexuals to have been smothered by maternal love, neglected by their father,
or sexually abused. And consider this: If “distant fathers” were more likely to
produce homosexual sons, then shouldn’t boys growing up in father-absent homes
more often be gay? (They are not.) And shouldn’t the rising number of such homes
have led to a noticeable increase in the gay population? (It has not.)
Homosexual people do, however, appear more often in certain populations. One
study (Ludwig, 1995) of the biographies of 1004 eminent people found homosexual
and bisexual people overrepresented, especially among poets (24 percent), fiction
writers (21 percent), and artists and musicians (15 percent). Gay more than straight
men also express interest in occupations that attract many women, such as decorator,
florist, and flight attendant (Lippa, 2002). (Given that some 96 percent of men are
not gay, most men in such occupations may nevertheless be straight.)
Men who have older brothers are also somewhat more likely to be gay, report Ray
Blanchard (1997, 2008) and Anthony Bogaert (2003)—about one-third more likely for
each additional older brother. If the odds of homosexuality are roughly 2 percent among
first sons, they would rise to nearly 3 percent among second sons, 4 percent for third
sons, and so on for each additional older brother (see FIGURE 11.15). The reason for this
curious phenomenon—the fraternal birth-order effect—is unclear. Blanchard
suspects a defensive maternal immune response to foreign substances
produced by male fetuses. With each pregnancy with a male
fetus, the maternal antibodies may become stronger and may prevent
the fetus’ brain from developing in a male-typical pattern. Consistent
with this biological explanation, the fraternal birth-order effect occurs
only in men with older brothers from the same mother (whether
reared together or not). Sexual orientation is unaffected by adoptive
brothers (Bogaert, 2006). The birth-order effect on sexual orientation
is not found among women with older sisters, women who were
womb-mates of twin brothers, and men who are not right-handed
So, what else might influence sexual orientation? One theory has proposed that
people develop same-sex erotic attachments if segregated by gender at the time their sex
drive matures (Storms, 1981). Indeed, gay men tend to recall going through puberty
somewhat earlier, when peers are more likely to be all males (Bogaert et al., 2002). But
even in tribal cultures in which homosexual behavior is expected of all boys before
marriage, heterosexuality prevails (Hammack, 2005; Money, 1987). (As this illustrates,
homosexual behavior does not always indicate a homosexual orientation.)
The bottom line from a half-century’s theory and research: If there are environmental
factors that influence sexual orientation, we do not yet know what they are.
This reality has motivated researchers to consider more carefully the possible biological
influences on orientation, including evidence of homosexuality in the animal
world, and the influences of differing brain centers, genetics, and prenatal hormone
exposure.
