Mom's Pills May Turn Daughters Into Lesbians - Study
Scientists Say More Research Needed
Special to World Science
Pregnant womens' use of certain diet and thyroid medications may lead their daughters to become lesbians, new findings suggest.
Researchers said the findings are very preliminary and need confirmation. But if borne out, they could put a new perspective on the hotly debated causes of homosexuality.
The researchers, Lee Ellis and Jill Hellberg of Minot State University, North Dakota, questioned more than 5,000 U.S. and Canadian women in an effort to determine the effects of drugs they had taken during pregnancy. They found certain types of pills were associated with a much higher rate of lesbianism among the women's daughters ñ though not with similarly raised rates of homosexuality among their sons.
The pills statistically associated with lesbianism included amphetamine-based diet pills and synthetic thyroid medications, primarily Synthroid and Thyroxine, used to treat disorders of the thyroid gland.
Mothers who had taken the diet pills were eight times more likely than other mothers to have homosexual daughters, whereas those who had taken the thyroid pills were five times more likely, the researchers found.
The study also found a third type of drug statistically associated with lesbianism in the daughters: DES, a drug prescribed to millions of pregnant women between the 1940s and the early 1970s, especially for those with histories of miscarriages. DES later fell out of use after research linked it with reproductive system cancers among daughters and sons.
According to the researchers, the findings provide partial support for a theory on the causes of homosexuality that has gained increasing currency among scientists in the past several years, the neurohormonal theory. This theory, of which Ellis was one of the original proponents, claims a person's sexual preference is influenced by the levels of sex hormones to which he or she is exposed in the fetus.
But Ellis and Hellman acknowledged the findings weren't completely in line with that theory. The two types of drugs which they found were most strongly associated with daughters' same-sex attraction ñ the diet and thyroid pills ñ aren't known to affect sex hormone levels. Rather, they affect the immune system.
The neurohormonal theory also says immune system factors can affect sexual preference; the placenta, a structure which supports the developing fetus, is highly immunologically active. But this is a less central aspect of the theory than its assertions dealing with sex hormones.
"Overall, it may be hypothesized that drugs affecting the immune system that are being consumed by the mother during pregnancy could alter brain development of the fetus in ways that affect later preferences for sex partners," wrote Ellis and Hellman in a paper on their findings, to be published in the January issue of the research journal Personality and Individual Differences. "Nevertheless, because there are neither animal experiments nor prior human studies to suggest that either amphetamines or thyroid drugs are capable of making such alterations, much more evidence is needed to consider this a well-supported hypothesis."