Ah, but it is true that people acquire tastes for foods and such. Beer for example - I've acquired a taste for it, though I didn't like it at first. Of late, I am fond of Sierra Nevada's Kellerweis. A Stone Cold Ruination is also good, but harder to find.
Yes, if one so chooses they can "experiment" and come away with differently. You are just being close-minded to think that everyone is made a certain way and there's nothing you can do about it. If anyone has a right to say anything on the matter its people who have done it.
Here's an example of where someone might "experiment": they come to the conclusion that sex is all about pleasure. It doesn't matter who your with, or even what - just so long as you enjoy it. And believe me - being in a college town - many people have this conception. Starting from here, they will try many things - one of which is experiment with gender. Historically, and even today, people will even do things with animals and such. Depravity knows no bounds. Would you say then that they were born with a sexual orientation of a horse or something? Of course not.