Congratulations to kjmtchl, the author of this incisive article. For more than ten years now I have been questioning in my own mind why scientists like Dean Hamer and his co-workers would want to look for a gene for homosexuality. Given the importance in evolution that attraction to the opposite sex has for the continuation of the species, this property could not be left to chance and would have to be encoded in our genes. Hence in the male of the species, the individual in most cases (in humans it has been estimated at 90%) is sexually attracted to the female and conversely the female is attracted to the male (by the same estimated 90% - this, as discussed below is probably not a co-incidence). So it seems to me that scientists should be trying to identify the gene (I use the term gene in the singular here for ease of expression although, in all probability, there will be a set of genes, and ultimately there will be many interactions when one comes to the question of sexual behaviour, some of which will be genetic and others will not be of a genetic nature) and the product of that gene that causes sexual attraction to the opposite sex as a starting point. As it has happened many times in the early studies in biochemistry, it has been the study of the abnormal (the word “abnormal” from here onwards, is used in the context of that of the minority of the human population, that is the 1 in 10) that has provided the first insights into the normal biochemical situation. Thus early studies on the family tree of homosexual males pointed to the fact the genetic trait of homosexuality carried by these individuals was inherited from their heterosexual mothers and later researchers concentrated their studies on the X chromosome. A heterosexual grandmother has a 1 in 2 chance of passing this trait to her children by way of one of her two X chromosomes), whether they be sons or daughters. The sons will have a 1 in 2 chance of inheriting the trait and those that do will be genetically homosexual (the “gay” uncle). The daughters will have a 1 in 2 chance of inheriting the trait and their sons (the grandsons) will in turn have a 1 in 2 chance of inheriting the trait. If the gene coding for “sexual attraction” is carried on the X chromosome in the gay male, is it not reasonable to conclude that the gene for determining sexual attraction in the remainder of the human population is also carried on the X chromosome? This is my starting hypothesis. The gay male has the same genetic coding as the heterosexual female – there is no mutation and no “gay gene” – just an inheritance by the male of a normal female gene. So in this 90% of the population, the two sequences of the genes on the X chromosomes (XX in the female) produce enough “product protein” to confer on the individual, an attraction to the male whilst with only one sequence there is only enough product protein to make the individual attracted to the female. The genet
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