There is little in biology that could be characterized as "simple". Variation in breeding systems (and the evolution thereof) is insanely complicated.
e.g. Many social female insects are born incapable of laying eggs. The stinger of a bee is a modified ovipositor.
Other social animals (like wolves, etc.) do not contribute to the gene pool directly because they never mate, but rather are part of a collective in which one male and one female are responsible for reproduction. I don't imagine, kkll4ever, that you have ever heard of "kin selection" but you should look it up.
Many fish and amphibians are born with one sex, but change sexes in response to environmental stimuli.
Flowering plants are often bisexual and capable of reproduction by selfing.
Nematode sexual classes are most often hermaphroditic and female, but not obligately male. Kinda gay, huh?
Fungi may have up to 27,000 sexual classes rather than just two, male and female. How Noah managed to distinguish these and get one of each on his boat should be an indication of his prowess as a mycologist, no?
And lets remember religious clergy who may be born "heterosexual", but in practicing abstinence produce no children at all. I suppose these too are an abomination.
One of the reasons religion has such a great draw is that, unlike science, its simple. If only simple meant right.
