With that subtle disclaimer behind us let's get to the meat of the question. Fyodor Dostoevsky's philosophical novel The Brothers Karamazov, gave the world the interesting aphorism, "If there is no God -then everything is permitted."
This is a morality discussion, and should be treated as such. Not a legal one and not a capability one.
Therefore, why should a man not rape a woman if he lusts for her--biology would have us do that. Why should a man not kill a coworker who threatens his job security--evolution has shown us this to be the case many times over.
Many people might say something akin to, it is for the preservation of society. But why preserve a society in which you have to control your 'natural' lust, or greed or aggression? Survival of the fittest, take what you can and screw the others.
It seems that everything we say is [morally] wrong (eg; killing gays/being gay, slavery, rape,
In short, if we are just clouds of atoms acting by non-rational causation as science would tell us, why not do as you wish?