An oddity of rhetoric is the constant effort by homophobes to label homosexuality as 'unnatural' -- yet the same people who are so declaredly interested in the naturalness of human behaviour only rarely decry vegetarianism, and never rail against that most fundamental of unnatural human practices, the wearing of clothing.
So let us consider the relative 'naturalness' of these and other things commonly found in the human pattern.
Homosexuality, first and foremost, is fairly well recorded in the, ahem, annals of history. Naturally, to the degree that ancient expressions of condemnation of it exists, this can only mean that the practice then existed to be condemned. Ancient accounts do not, by contrast, condemn internet addiction because there was no such thing at the time. But, turning our focus to nature itself there are, it is now well recorded, hundreds of animal species in addition to humans who are happy to provide an example of how to gay up the jungle (or the woods, or the icy Antarctic floes). So, though opponents of the freedom of those who would engage in homosexual acts deem the predisposition toward same-sex-attraction to be a matter of choice, nature itself instructs that this is a natural choice to make.
Vegetarianism is indeed a far less 'natural' practice, man being an omnivore by nature (and prehistorically quite a big bug-eating insectivore on top of that). But this observation lays out the crux of another question: is there anything wrong with doing things in a way which is contrary to the practice in nature? Here is starker item of comparison. Suppose a lost teenage boy from a different city came wandering onto your property, looking for something to eat. What would you do? Well, going back to the ways of our prehistoric forebears, you'd kill him. Or, at least, you'd try, try to drive him off with sticks and stones, and if he persisted in loitering in your neighbourhood, to make a more level effort to end his life. Nature is violent. However peaceful it may appear in the moment of a quiet glen or solemn wood, it is filled at every moment with the predator aiming to kill, and the prey animal avoiding sudden death, and with competitors from the same species contending over turf and resources, often with deadly results. Other animals may even kill competitors to punish them for their own attacks against the territory of the killers, even to make an example of them before their peers. True though it is that man has a broader range of reasons for killing, and methods of so doing, man is as well the only animal for which members of a tight-knit social group will contend to prevent one of their own from engagin in violence against a stranger. And, though many animals are vegetarians by dint of their biology only permitting the digestion of plant matter, man remains the only animal fully capable of eating and digesting meat which will naetheless choose to refrain from eating meat when it is available, plentiful, even. For man is the only animal possessing ethical purposes, and so, the only one which acts against its own nature in defiance of his biological compulsions.
Now let us look at clothes wearing, and its natural converse, nudism. Wearing clothes, it may not seriously be denied, is highly unnatural. True, there are creatures like crabs and turtles who are oft anthropomorphised as treating their shells like clothing, or as externalities wherein they make their home. And there are indeed some small number of exotic species, mostly kinds of crabs biologically alien to us, who assemble for themselves a carapace incorporating bits of material from their environment, instead of grown from their bodies. And yet humans in most (though assuredly not all) cultures around the world have adopted the practice of draping themselves with cuts of cloth situated for the coverage of uncomfortably exposed body parts. This is to a degree an expression of the evolutionary process, for man came to be man on African plains where bodily hair for warmth could be disposed of, and so did the bareness of human skin evolve. But then man spread out in a way that few other large animals ever do. And in so doing, man encountered climates which demanded cover against the cold, and indeed it was man's intellect, man's ability to defy nature even, which enabled the spread of the species to prevail even into arctic climes. Clothedness, then, was never any thing which originated in response to some imagined wrongful character of nakedness. To be sure, every human being is still born unclothed, though perhaps the prudes will someday imagine up a way to clothe the baby in the womb, so it is delivered with its naughty bits inoffensively covered. And even the most prudish, even the ones who have campaigned in the past to require zoos to put pants of chimpanzees, unashamedly experience at least some moments of nakedness in their homes, unless they are so pathological in their objection to nudity that they bathe, shower, sleep, and have sex all while clothed (or that they do none of these things).
A few other modern mores venture into the exceedingly unnatural. Monogamy, and its corollary legalistic expression, marriage. Precious few species of animals out there really do mate exclusively, or for life, and man in his natural state is decidedly not amongst them. Eating food which is cooked (no matter whether flora or fauna)? No beast of the wild does so except by some bizarre circumstance following a forest fire or volcanic eruption. Abortion? Animals experiencing scarcity while pregnant will give up their unborn rather than have it born into hunger which can not be fed -- though this is an unchosen process more akin to miscarriage than to the human activity of abortion, though that practice in humans may well be an expression of the same natural instinct. But the practice of going to a clinic for a late-term procedure to exact revenge against the wayward father of the fetus, that seems a more unnatural thing. In sum, there are a great many things which fall within not only the permissions, but even the expectations of our society which are deeply unnatural. But before anyone comes to condemn any behaviour for being unnatural, for God's sake, they ought to take their damned pants off!!