Is it true that there is no absolute morality?

[bennyboy]

That really side-steps the issue, at least with respect to moral nihilism. Having preferences and natural instincts are not the same as having obligations or moral prohibitions.

I don't want my daughter raped. I talk to the next five dads I meet. Not surprisingly, they all stand pretty clear on the "no daughter rape" policy. Knowing that this idea is common to the human experience, we will be together able to determine that someone who thinks daughter rape is okay is dysfunctional. Because that's what "evil" is-- something which is seen as so against good function that it is abhorred by almost all of us.

I'm not sure why you think there's a big mystery here. If dogs were smart enough to write on tablets, they'd write, "Thou shalt not steal thy neighbor's bitch nor unearth his bones."