- 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
- 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
- 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."