Did you read the last sentence in my post?
Human females can conceive only three days per month, yet they're receptive to sex all the time (in theory--my experience has never confirmed this). That would be an enormous waste of resources and energy if procreation were the only evolutionary function of human sex.
You're assuming that female sexual receptiveness isn't just an accident.
Additionally, female sexual receptiveness probably serves a socially adhesive function; males would stray from the nest if females were only receptive for a week every month. There's a survival issue. (I suppose you could argue that that since male homosexuals are "receptive" 24/7/365, they're even better suited for survival in a social sense, (except of course for the minor detail that they can't reproduce...))
When we ask if someone is "responsible" for his conduct, isn't that a moral inquiry?
I *thought* the moral issue arose when we tried to deicide if the person's actions were "right" or "wrong" (given that they were voluntary in the first place...)