Sex contrary to the traditional meaning of sex is similar to the "stolen concept" fallacy Rand talks about. It accepts some premises of the traditional sex positions (like the stuff about sex being good and important), while also contradicting a bunch of them. The result is illogical nonsense.
If sex plays a traditional role in your life, I understand. If sex plays no significant role in your life, I understand. If sex plays some other role in your life ... wtf are you doing? Don't actively fight with your culture over sex. Do something productive.
Many people believe homosexuality isn't a choice. I don't know if they also believe BDSM isn't a choice. But who you have sex with, and what your ideas about sex are, actually is a choice.
Some of these choices are made in early childhood and people are confused about how to change them later. People also create anger problems in early childhood and are confused about how to stop being such an angry person later in life. That doesn't make anger a non-choice. It's just a bad choice that's somewhat hard to undo later (many bad choices have lasting consequences).
The "homosexuality is not a choice" crowd are very confused. They say it's genetic. But if it was genetic it'd be easier to change. Hair color is genetic and is changed by dye. Eye color is genetic and can be changed with colored contacts. Having a right arm is genetic, but can be changed with an axe.
What's really hard to change in life isn't genetics, it's memes. Genetics offer a limited obstacle but don't actively do anything to stop you from changing. Memes aren't set in stone at birth, like your DNA; memes can adapt as you try to change. Static memes also have much more knowledge in them than your genes.
Homosexuality isn't all that hard to change. The reason people find it very hard to change is because they're really, really bad at changing. Plus they generally give up without trying, or don't want to try to change.
The reason changing is hard is that people hate thinking. If they liked thinking they'd participate in rational discussions, but they don't want to do that.
To be clear, I am not recommending homosexuals and others change right now. Many of them have bigger problems that they'd be better at solving. E.g many of them are parents and ought to stop hurting their children as a higher priority. Anyway, pointing out mistakes and problems is valuable and worthwhile, but doesn't imply those mistakes and problems should be one's immediate focus for change.