As for incest being good because it could cause webbed hands and feet, which could be better for swimming - I think the answer to that one lies in that keyword 'could', as it's far more likely that an child born of incestuous parents could turn out with hemochromatosis, which is probably something that's a little less evolutionarily beneficial. I think that all the crazy eugenics research has proven that incest is probably a bad idea. Now, as to whether we should 'allow' incestuous relationships? That's another ballgame completely. Is it illegal for a mother to smoke cigarettes or drink while pregnant (I think not, but I really can't be arsed to cite this) - this could ultimately also cause birth defects, premature birth and whatever else, however - it's not quite abortion. Abortion is purposefully 'killing' the child, however if a defected child is born - it's still born, and can still - by definition live it's life. 'Another related issue is homosexuality which is also detrimental to evolution' However, an extreme would be that survival is more important than evolution - therefore, if somebody believed they'd live a more prosperous, comfortable or whatever life due to homosexuality, they'd choose to be homosexual. After all, this is a completely level-headed and fair argument, as no researcher has found (although I realise this doesn't mean they don't exist) any genetic or biological differences between homosexual and heterosexual people, so one could say that their environment modelled them to be homosexual. 'People can't choose who they are attracted to, or who they fall in love with.' I beg to differ there. The only studies that would back that opinion would be attraction to natural smells, and looks. These are natural defences to prevent incestuous relationships, however, environmental differences can help sway these natural 'safeguards'. 'If you accept that nature made some people homosexual and gave other people sickle-cell genes, then why can you not accept that nature made some people incestuous?' I don't accept that 'nature' makes people homosexual, as what I've already stated, no 'gay gene' has been found, although it has been disputed. Sickle cell, on the other hand, is quite different, and isn't completely evolutionarily detrimental. Sickle cell anaemia suffers are immune to malaria, which actually creates a survival value in carrying the genes. (Also, please bear mind to sickle cell trait) I'm still quite a sceptic to people being genuinely attracted to their sister. The science just seems to point to many other conclusions than 'nature did it',,, -Lynx (Ps. I'm drunk and tired, so will edit later)