[frog in a pot]

But it would not be an identifiable mutation except under extreme circumstances.

Not sure I follow that, but then I am not a scientist.

I would argue the results of such an atypical prenatal development that we are discussing would not be difficult to identify, and are often readily apparent even to a lay person. I.e., there is reason to believe there was indeed a mutation.

With that, rather than my earlier reference to a “mistake of nature”, it would have been more precise to say nature reliably produces those results and our effort should be to identify the mechanisms of causation.

[Regulator]

The point about it is that genes do not mutate under environmental pressure during natal development.

Lysenkoism is a cardinal sin in the biology world...although late breaking news is that there might - and only might - be an environmental pressure that leads to genetic mutation by protein modification, the emerging field of Epigenetics.

Doubt if anything as complex as homosexuality would be the result of such a thing.