I recently read a book that explored the 'causes' of same sex attraction and, given that most homosexual people don't propagate, why male (Female homosexuality has not been seriously studied) homosexuality has not died out

I don't have the book to hand - I am not home - but there were two hypotheses put forth:

1) It is possible that the 'gene' is carried in the female siblings of a homosexual male and transmitted to their own progeny to emerge farther down the line. There is some evidence to support that possibility.

2) The other postulation is that homosexual males have been persecuted, for generations, so that it has not been safe to come out, and therefore many men have married and had children, never daring to live openly according to their own desires. That, of course, does not mean that these closeted men have not had homosexual contacts- just look at some recent infamous examples of that- nor does it address bi-sexuality.

But they concluded that if #2 turns out to be the correct answer, the possibility exists that the incidence of homosexuality will decline as it becomes safer.

Speaking of 'safer', ake, you bang on about the "horrendous" health risks that homosexuals face- but I have never heard you say a word about hang-gliding, ice-climbing, mountain-climbing, or bungee jumping, or even the most dangerous activity of all: commercial fishing. You might even say that it is catching, since many children of the risk takers take up the same lifestyle.

For that matter, many children of obese parents also become obese, What should we do about it?