Is Polyamory Genetic? Is Homosexuality Genetic?

So Ministry_victim asked an interesting question:
“I’m interested in hearing your thoughts on the ideas of those who believe that polyamory is an a priori genetic condition that suggests predisposition a la homosexuality.”
My thoughts on a genetic polyamory link are the exact same as my thoughts on a genetic homosexual link:
I don’t care.
Now, I do believe that there is some genetic predisposition towards homosexuality (and gender dysphoria leading to gender switches).  As many have noted, people don’t become gay for the fabulous social benefits it brings.  And I’m as guilty as any of occasionally dragging this fact out to try to convince the anti-gay faction that they should be more tolerant of homosexuals because gay people can’t effectively change the nature of their attraction.
But if.  Even if.
Even if the gays were, as some suggest, all conspiring in one big plot to annoy us fine-thinking straight people, wincing as they sucked distasteful dick and reluctantly chowed pussy out of some misplaced form of rebellion, it should still be allowed.
The truth is, gay sex is between consenting adults, and it hurts no one but those adults – there are way more deadly car accidents caused by beers than queers.  You may consider gayness to be a bad choice, but two people should be free to make bad choices together.  And what people want to do for fun in their private life is something that should be allowed, no matter how distasteful it may be to me.  There are scat-players out there, an act that fills me to the bottom of my throat with ick, but as long as they keep their apartment clean for their poor landlord I say let ’em do as they please.
(I’d even say let ’em wear outfits proclaiming their love of scat in a public place, but in the interests of public niceties I do request a shower before they get on the subway.)
Let’s say there are people who are indoctrinated in a seditious lifestyle, pestered into a culture that preys upon naive young people who don’t know any better, at which point they are ushered in and secluded from society and brainwashed until they come to believe that all of these evils are not just acceptable, but actually natural… And then they go out seeking new victims.
Well, there are, and the born-again Christians ring my doorbell early Saturday mornings, and I’m not looking to outlaw them.  (If they offered free hummers as part of their entry package, I might be more willing to listen.)  As such, even if gay people were an act of rebellion, I’d still say it was something that should be allowed.
We often get caught up in the “nature vs. nurture” aspect of gay and transgender issues, forgetting that this is playing to the conservative bent.  What’s important is that people all over the world should have the freedom to live their lives as they see fit assuming they’re not actively harming anyone, and as such Teh Gay Should Be Okay.
So is gay genetically disposed?  I say probably, but it doesn’t make a damn bit of difference.
Now; is polyamory a genetic tendency?  That, I have no opinion on.  I’ve gotten in trouble for my assertions that polyamorous people are, by and large, much larger horndogs than the average person – which makes sense to me, given that you’re risking breaking existing relationships in search of new sexual intimacy.  (Otherwise you could just, you know, be friends.)  I’m sure there are tendencies genetically towards certain aspects that encourage polyamory, but polyamory is such a complex term, encompassing so many styles of relationships, that I don’t think a single set of genes could really cover it.
But it’s irrelevant.  I’ve heard it said that after gay marriage gets settled, they’ll be coming after the polyamorous relationships next.  Could be.  When that day comes, the genetic predisposition will be just as useless.