Most Are Straight, Some Are Gay, and Why It Is That Way: The Science and Future of Sexual Orientation

This essay is co-published by <>, 2015

Should same-sex marriages “be recognized by the law as valid, with the same rights as traditional marriages?” In 2015, a record 60 percent of Americans told Gallup yes; only 37 percent said no. This flip from the 37/59 percent split a decade earlier (and from the 27/68 percent split of 1996), represents an astonishing transformation of public opinion. This momentum of gay support will likely continue as gay friends and relatives continue coming out, and as attitudes follow behavior (with same-sex marriage now the law of the land).

Equally striking is an enormous generation gap. Averaging across surveys, support for same-sex marriage runs about 40 percent among Americans over age 65 and nearly 80 percent among those ages 18 to 29. I am unaware of another social issue about which older and younger Americans so dramatically disagree. Today’s millennials and their grandparents live in different social worlds. Together with changing public opinion, the generation gap is forging a new social reality. Generational succession is destiny.

And should “homosexuals . . . have equal rights in terms of job opportunities?” From 1978 to 2008, the number telling Gallup yes skyrocketed from 56 to 89 percent.

Whatever our own opinions, perhaps we Christians can agree on two things:

  1. Our teaching of sexual ethics should not simply follow cultural trends. Rather than put our finger to the wind, we should put our nose to the Bible, aided by scholars who can help us discern its wisdom for our time.
  2. Public opinion surveys are like a car’s speedometer—they don’t drive the car, but do tell us how fast we (and the traffic around us) are moving. Today’s cultural traffic motivates our stepping back to understand what science has discerned about sexual orientation, and also to reengage biblical wisdom pertinent to human sexuality.

Sexual Orientation: The Numbers

European and American surveys, administered to random samples and with anonymity protected, indicate that about 3 to 4 percent of men and 2 percent of women report exclusively same-sex attractions. To explore sexual identity, Gallup asked 121,290 Americans: “Do you, personally, identify as lesbian, gay, bisexual, or transgender?” Yes, answered 3.4 percent. (For detailed citations regarding these and other findings in this essay, see my Psychology, 11th Edition, Worth Publishers.)

Does disapproval of homosexuality decrease it? On Facebook, the percent of men who publicly express a same-sex preference is 3 percent in tolerant California and 1 percent in disapproving Mississippi. Yet our culture’s increasing acceptance of same-sex relationships has not been accompanied by a notable change in the proportion of straight and gay people.

And consider this: conservative, religious Southern states generate more than average Google searches for sexually explicit content such as “gay sex” or answers to “Is my husband gay?” (MacInnis & Hodson; Stephens-Davidowitz). The number of Craigslist ads by men seeking “casual encounters” with other men is likewise at least as large in less tolerant states as in more tolerant states. And in African countries, where same-sex relationships are generally illegal, the gay–lesbian prevalence “is no different from other countries in the rest of the world,” reports the Academy of Science of South Africa. The bottom line: Whether a culture (or church or school) condemns or accepts same-sex unions, heterosexuality prevails and homosexuality exists.

Sexual Orientation Is a Natural Disposition

Multiple lines of research converge in indicating that our sexual orientation is something we do not choose and, especially so for men, cannot change.

Postnatal environmental influences are unknown. Sexual orientation has no known environment influences. Contrary to what Freudians and kindred reparative therapists have assumed, same-sex attractions appear not to be the result of child abuse or molestation, or a distant father and domineering mother. If distant fathers engendered gay sons, then shouldn’t boys growing up in father-absent homes (and in modern times with more absentee dads) be more often gay? (They are not.)

Having followed this research closely for several decades as a reporter of psychological science, what advice could I give to a young couple wondering how they can shape their newborn’s sexual orientation? My simple answer: I haven’t a clue. In the biggest behavior genetic study, the home environment’s association with sexual orientation was zero. So let us “judge not” parents for the sexual orientation of their children. And let us love our children as they are.

Same-sex attractions are displayed by many animal species. A first clue that sexual orientation is, instead, a natural, biological phenomenon comes from the several hundred species in which same-sex sexuality has been observed—from gorillas to grizzlies, from flamingos to owls. Among sheep, some 8 percent of rams shun ewes and seek to mount other males. Homosexuality, like heterosexuality, is part of the natural world.

Gay brains and straight brains. Neuroscientists have discovered several gay–straight brain differences. One, observed in post-mortem hypothalamus tissue, made people wonder: Does this brain difference help explain sexual orientation? Or do people’s sexual experiences leave fingerprints in their brains? Further research suggests that the brain difference is more cause than effect. It appears very early in life, and it is present in those male sheep that display same- versus other-sex attraction.

Male and female brains, and gay and straight brains, also respond selectively and automatically to various sexual stimuli, including sex-related scents. Thus, surmises researcher Simon LeVay, “Gay men simply don’t have the brain cells to be attracted to women” (121).

Genetics and sexual orientation. What causes the brain differences associated with sexual orientation? Is it genes? Prenatal influences? Or both? We’re not formed just by our genes. Genes get expressed in environments, rather like a tea bag expressing its flavor in hot water. But genes matter. Although not inherited in the straightforward way of eye color, twin and family studies confirm that sexual orientation is influenced by genes—many genes having small effects. One recent genomic study of 409 pairs of gay brothers identified sexual orientation links with parts of two chromosomes, one maternally transmitted.

But why, given that same-sex couples do not naturally reproduce, would “gay genes” exist in the human gene pool? Several studies have found that 1) homosexual men tend to have more homosexual relatives on their mother’s than on their father’s side, and 2) their heterosexual maternal relatives tend to produce more offspring than do the maternal relatives of heterosexual men. Perhaps, then, suggests a “fertile females theory,” the genes that dispose women to be strongly attracted (or attractive) to men—and to have more children—also dispose some men to be attracted to men. Thus, there may actually be reproductive wisdom to genes that dispose some men to love other men.

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Works Cited

Chambers, Alan. “Exodus Int’l President to the Gay Community: ‘We’re Sorry.’” Alan Chambers. Web. Accessed 25 June 2015. <>

“Diversity in Human Sexuality: Implications for Policy in Africa.” Academy of Science of South Africa, May 2015: 36. Web. Accessed 23 June 2015. <>

LeVay, Simon. The Sexual Brain. Cambridge, MA: MIT Press, 1993.

MacInnis, Cara C., and Gordon Hodson. “Do American States with More Religious or Conservative Populations Search More for Sexual Content on Google?” Archives of Sexual Behavior 44 (2015): 137–47. Print.

Myers, David. A Friendly Letter to Skeptics and Atheists. San Francisco: Jossey-Bass, 2008.

Paulk, John. Quoted by Steffan, Melissa. “Former Ex-Gay Spokesman John Paulk Apologizes Amid Divorce.” Christianity Today: Gleanings. Posted 2 May 2013. Web. Accessed 25 June 2015. <>

Smid, John. “Where Is the Repentance?” Grace Rivers. Posted 7 Oct. 2011. Web. Accessed 25 June 2015. <>

Stephens-Davidowitz, Seth. “How Many American Men are Gay?” New York Times 7 December 2013: SR5. Web.

David Myers serves as professor of psychology at Hope College in Holland, Michigan.