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The search for the gay gene

BMJ 2005; 330 doi: https://doi.org/10.1136/bmj.330.7498.1033 (Published 28 April 2005) Cite this as: BMJ 2005;330:1033

Gay genes and zinc deficiency

It is interesting that Hamer and colleagues previously found a
linkage between DNA markers on the X chromosome and male sexual
orientation.1 Now they also report approximately equivalent maternal and
paternal contributions at a position near D7S798 in 7q36 (mlod score 3.45)
and also near D8S505 in 8p12.2 (mlod score 1.96).2

Dr Gibbon refers to Moir and Jessel’s book “Brain Sex” noting that an
excess of male homosexual children can arise as a result of influences
during pregnancy such as hormone therapy or severe fright.

Besides distorting hormone levels in a developing foetus, maternal
hormone therapy can cause zinc deficiency, as does fright or famine. Zinc
is not only essential for normal brain development and function but it
also needed for normal testosterone production at the critical times of
brain sexual development. Homosexuality and dyslexia are more common in
males than in females, perhaps because males have a greater need for zinc.

Homosexuality and dyslexia seem to have both genetic and
developmental components in early pregnancy. Gene expression can be
altered with different balances of zinc and copper. Maternal zinc
deficiency may prevent the development of the usual degrees of cerebral
dominance in either right or left hemispheres causing cross laterality. In
tests of special ability homosexual men scored lower than heterosexual men
but higher in tests of verbal fluency. Their cognitive abilities were
intermediate between those of heterosexual men and women.3

I do not understand why women with unexplained infertility are given
sex hormones and gonadotrophins. Exogenous hormones can increase zinc and
copper imbalances which too often remain undiagnosed and uncorrected
before conception.

1 Hamer DH, Hu S, Magnuson N, Pattatici AML. A linkage between DNA
markers on the X chromosome and male sexual orientation Science
1993:26:321-27.

2 Mustanski BS, Dupree MG, Nievergelt CM, et al. A genomewide scan of
male sexual orientation. Hum Genet. 2005;116 :272-8.

3 McCormick CM, Witelsan SF. A cognitive profile of homosexual men
compared to heterosexual men and women. Psychoneuroendocrinology
1991;16:459-73.

Competing interests:
None declared

Competing interests: No competing interests

01 May 2005
Ellen C G Grant
physician
Kingston KT2 7JU, UK