Oh I don't think there is any question about it at all, it obviously is an natural tendency for a small "genetically isolated" minority of both man and animals.
However...
You are still ignoring the point re the difference between man and animals, the volitional and reasoning abilities which man has and animals don't. This difference is far from "irrelevant". Man can know the hootus in the anus is illogical and unreasonable because he is man, animals cannot know the hootus in the anus is illogical and unreasonable because they are animals. (BTW it's hootus not hooter, hootUs as in "How Do I Get Herculiner Off of My Hootus?!"). Pure "natural tendency" is called instinct and is something animals cannot rise above without the reason and volition that only man has. When man refuses to use his reason and volition he reverts to inborn animal instinct and acts like animal.
"If humans live in genetically isolated tribes, as they did for about 3 million years, give or take a tad, then investing in your tribes collection of your near relatives, rather than in your own personal DNA destiny, is bound to be a cinch bet for your DNA."
But humans don't "live in genetically isolated tribes" these days do they? This is the 21st century, Man. Man is not a bird. Man is not an animal (even though he sometimes acts like it.) Human women have two holes. Human men have only one. Every man can be the alpha male of a family unit as there are plenty of women. But not when he chooses the stinky hole. My brother does not provide resources for my children. I do not provide resources for my sisters children. I provide resources for my children. My two uncles do not provide resources for me, in fact they ripped off the inheritance from their siblings and their siblings children. A chicken might tell you none of this is not true. But a chicken is, after all, a chicken and Man, is Man.
So get with it, Man.
"Practicing sodomy is like taking a crap on your keyboard before you type. A high percentage of marriages end in bitter divorce. A disturbing percentage of those same marriages manifest domestic violence. Clearly, practicing heterosexuality is like taking a crap on your keyboard."
You brought up using fingers for the "unatural act" of typing as a pitifully anemic analogy in "defense" of sodomy. Stay focused. No one takes a crap on their keyboard before typing. No one has to give either their fingers or keyboards enemas before typing. Your analogy stinks, just like sodomy.
Right. Because we live in good times, and not in the isolated tribes where our behavior was bred, so we pretty much all want the luxury of pair-bonding, even though few of us are alphas. If you want to make a homosexual, there's nothing to it--deprive him of his parents, feed him irregularly, accompanied with disdane or outright abuse, make sure he never feels like a competent person, much less a leader regarding anything, and by the age of 18, you will have a full blown sissy man, flat out guaranteed. That's what accounts for the presistent presence of homosexuals--ask wherever homeless kids hang out in your city if you need vivid evidence--these kids are doing exactly what wolves do--trading sex for survival, not babies. That is what accounts for the vast majority of homosexual behavior, and it is plainly obvious that it accounts for most of the 3 to 10 percent that is being pointlessly niggling over here.
Give a kid the right signals, and just as nature intended, he will instinctively make the right choices for his gene's best chances. That is exactly what street kids and other prostitutes do--you couldn't ask for a more graphic demonstration. You are unlikely to procreate at all if you are dead of starvation or exposure or gangrape before you attain your majority--just as is the case with wolves.
And how is that not precisely my frequently re-iterated point?
You are still ignoring the point re the difference between man and animals, the volitional and reasoning abilities which man has and animals don't.
If I am ignoring your point, I am only returning the favor. As to reasoning ability--what is the reasoned recourse of an abused homeless kid close to dying of exposure on a cold rain, when offered a warm bed for the night? How is it different for that of an outlier wolf about to have his neck bit open by an alpha male?
Apparently, you do your reasoning from a nice, safe, warm spot in front of an expensive computer, which, in my opinion, distorts your judgement on this matter.