Environmental Factors and Sexual Orientation

Article excerpt


Mark Twain said once: "Rumors of my death have been greatly exaggerated." If environmental factors in sexual orientation could talk, they might say the same thing.

For sure, social or family factors in influencing sexual attractions have been written off by numerous scholars and media. However, a new Danish study may prompt a fresh evaluation of the role of social factors in sexual orientation.

The study, in this month's issue of Archives of Sexual Behavior, authored by Danish epidemiologist Morten Frisch and statistician Anders Hviid, reports the analysis of data from more than 2 million men and women. It is the first study to examine an entire group of homosexuals for environmental factors in their decisions to pair up homosexually. The research suggests a link between environmental factors such as geographic birthplace and family relationships and the probability of marrying a same-sex or opposite-sex partner.

The massive study also finds the number of brothers and sisters increases the probability of marrying heterosexually. This finding questions a recent, widely touted Canadian study of birth order that found the number of older brothers increased the probably of homosexuality in men.

Danish researchers found no evidence that having older brothers increased the likelihood of men marrying homosexually. On the contrary, they found that older siblings increased the probability of heterosexual marriage. The choice of homosexual versus heterosexual marriage serves as an obvious, though not perfect, assessment of sexual preferences.

Regarding the fraternal birth order effect, the authors said, "We found no indication that older brothers were particularly common in these homosexual men."

The researchers found for each additional year one's parents stay married, the probability of heterosexual marriage in the children increased 1.6 percent among sons and 1 percent among daughters. In contrast, the rate of homosexual unions decreased by 1.8 percent among sons and 1.4 percent among daughters for every year of intact parental marriage. Summing these effects over years of childhood and adolescence contributes to a noteworthy effect.

On homosexual marriages, the researchers found birthplace relates to the sexual orientation of marriage partner. Being born in urban settings increased the probability of homosexual marriage and decreased the probability of heterosexual marriage. Drs. Frisch and Hviid noted, "Our study may be the first to show that birthplace or some correlate thereof influences marital choices in adulthood. …