The whole issue of evolution and creationism is so emotional and controversial here that I am not going to touch it. People tend to sway to one side or the other, but the holes in each are numerous, and at this point in time there is a lot of "theory". So I will leave it at that.
In terms of Keith Richards, he did have a daughter that died shortly after birth in the 70's. And it was during a time that he was heavily addicted to junk. And the mother was a hardcore addict as well. His first child was born to the same mother in I believe 1968, and at this point, he was a partier, but nothing like the 70's. I have read numerous interviews with him and commentary by other people, and he was functioning in the 60's. In the 70's he eventually had to have all or most of his teeth replaced. It is a similar story with all hardcore addicts, especially heroin. If you look at Garcia, who died in 1995 at 52 or 53, well his MD who was treating him at the end will say it wasn't the heroin that killed him. It was all of the baggage that the heroin brought. Such as the intense cravings for nicotine, so he smoked like a fiend, and the poor diet he was on while addicted, which at times consisted mainly of Ben and Jerry's, and the sleep, or lack of sleep patterns that it fostered. The periods he was clean he actually way cut back on all of these bad habits, and was living a fairly healthy lifestyle. And lost some of the excess weight. Throw in the heroin and he lost control of all aspects of his life and health.
Richards was similar. His teeth were replaced because of the years of heroin addiction that caused him to not care. He broke up with his first wife, met someone new in 1979 when he gave up heroin, married in 1985 and now has several daughters from this new marriage. And they all appear healthy and normal, at least on the outside.
I do think it is more complicated then we know at this time. Richards father lived to an old age (somewhere in his 80's) and drank and smoked pretty hardcore. My best friend died of leukemia when he was 15 and his two brothers are still around. Was it a bad sperm or egg that was the bulk of the problem? A random mutation? They didn't live next to a powerline etc. and the father and mother were both pretty straight, so to speak. And the brothers were close in age so their diet was probably pretty similar when averaged out over those years. Did a lack of a certain mineral, vitamin, nutrient when the actual sperm or egg was produced cause problems, even though the diet wasn't bad when averaged out? Was it a reccessive gene somewhere? Was it any of countless different other scenarios? We will never know, at least in his case.
But I do think gene research should be a priority. And people should keep an open mind to all of the different theories. But we are just barely scratching the surface. Even if we can write off a lot of it to bad lifestyle, which encompasses a lot of things, it won't explain everything. It is very complex. And it affects just about everything. Is there a gay gene? How much does environment play a role? If there is, does a bad or healthy lifestyle by the parents lessen or decrease the chances of a gay child?