So what would be their explanation for a heterosexual couple who choose to have only one child who turns out to be bisexual or gay?
It would be the same, the gene “would influence a woman’s sexual attitude (but not increase her fertility)”. If the couple use contraception for every sexual encounter from the conception of the first child then they wouldn’t have any more children. Really it just makes women more likely to want sex.
Yet more nonsense based on the idea that we are naturally heterosexual and something goes “wrong”, rather than that we are as a species almost all bisexual with a natural distribution of people at the extremes of the bisexual range. These guys are more like muppets than like scientists.
But as I understand it aren’t they only saying heterosexuality is normal in the same way being female is normal but something goes wrong and makes people male.