Harry Benjamin's Syndrome
Its usually
interesting to identify the starting biases of commentators when they have
something to say on transsexualism. The statements below demonstrate quite
clearly that, at least so far as the author is concerned, all transsexuals
start out as either cross-dressers or transvestites. In this he is simply
expressing a received wisdom. The statements are no more than transgenderism
writ large: but are they correct?
The first inference (assumption) is that transsexualism is a behaviour. The
next argument is that genetic or physical identicalness must always result in
the same behaviours before a genetic cause can be attributed.
“Only about 5% of cross-dressers, or transvestites, have any desire to be the
opposite sex, but those who do are often convinced they are a woman in a man’s
body,” writes Whitehead. ( Is transsexuality biologically determined?, Triple Helix (UK),
Autumn 2000)
“So how do you decide whether you were inescapably born that way? Try using
twin studies. Identical twins have (virtually always) identical genes. This
means they are identical physically, but do they have identical behaviour? If
one twin is homosexual, and homosexuality were genetically determined all
co-twins would always be homosexual. But it is now known that the percentage of
homosexuality among co-twins is 11%. “
“However of four studied monozygotic (identical) male twin pairs, of which one
was transsexual, the other twin was transsexual in only one case, and
researchers concluded that genetic factors were most unlikely to be important
(Buhrich, Bailey & Martin, 1991). If genes compelled transsexuality all the
co-twins would have been identical. More generally, Michael Bailey (a gay
researcher), maintains that for any behaviour (including homosexuality) the
genetic influence is 50 ±20. In other words no behaviour results exclusively
from genes.”
Good ole Michael J Bailey. But hang on. Bailey has been de-legitimizing HBS
folk for years. Well before they'd taken back Benjamin's name. Anyway there's a
minor problem (or three) in his analysis.
In the eighth edition of Developmental
Biology, researcher Scott F Gilbert gives a number of examples where
monozygotic (coming from the same fertalised ova) twins can be very different.
They can even be different sexes!
“It is usually assumed that monozygotic twins always share the same genome and
that their hereditary endowments are the same. Indeed, twins have long been
used in studies that attempt to separate "nature" from
"nurture". Gilbert writes.
[But] take the situation of an egg fertilized by a Y-bearing sperm. It has been
found that monozygotic twinning is associated with higher than normal amounts
of aneuploidy; so it is possible that if twinning were to occur through the
failure of the first two blastomeres to adhere to one another, aneuploidy
(abnormal Chromosome numbers) might also occur. In that case, the twins would
have different chromosome complements. If the aneuploidy were for the X
chromosome, one twin might by male (XY or XYY) while the other would be female
(XO).
And that's the problem with assumptions! The first assumption Whitehead makes
is that HBS is a behaviour. It isn't. Its a variation in foetal sex formation. The
second assumption is the usual chestnut, that if one identical twin is is
transsexed (HBS), they both need to be before the cause can be attributed to
genes.
Okay...its just one more hoary myth to throw in the faces of the biology
deniers, but its interesting, and besides, you can astound your friends at
parties. More importantly twin studies can not always be taken for granted in
nature/nurture arguments as indications of none genetic influences.