The article is not necessarily flawed science. It is more a statement that despite speculation, no gene associated with homosexuality has ever been found. A scientific proof would require that the gene be produced(you can not prove a negative hypothesis of existence.) Could the action of several genes or gene defects produce homosexual behavior? Perhaps, but that is speculation, and runs afoul of the general evolutionary principle that in the long run genetic outcomes that reduce successful reproduction are eventually removed from the pool. The argument that a homosexual gene combination might exits to ‘solve’ some other existential problem is literally a solution in search of a problem; possible I suppose, but not a very strong argument. In my opinion, homosexuality is much more likely a function of the wide innate range of human emotional response, or is derived from conditioning.
The general evolutionary principle does not apply to the misexpression of genes because misexpression is not carried forward in the genes.
Hermaphroditism is an example of this.
Hermaphrodite’s genes are perfectly normal however during fetal development their bodies do not develop correctly and they can not reproduce.
Yet hermaphrodites continue to occur in the population as they have throughout history.
But I still assert that the arguments made be the author are bad science. Perhaps he can make other arguments to support his assertions that are valid I don’t know.
It may be that some environmental factor could trigger a gene that normally would do some other function or do nothing at all malfunctions to express as homosexual desire.
I do think that some but not all homosexuals are born that way. There are simply too many reports of children expressing homosexual proclivity at a very early age to discount the occurrences.