I can buy this explanation in a completely different universe, but not when it's just a different timeline. The example that's close to OP's, but I think works better, is with Star Trek, where Sulu is straight in the main timeline but gay in the alternate timeline, even though they do have the same DNA because it's just a different timeline which only split around the time of Kirk's birth, and they started in the same place. So there, they pretty much just confirmed that it is a choice.
Then again, that's the same franchise where a timeline splitting in the 2200s caused Khan to change from a swarthy spanish man to a pale alien looking white guy even though he was born in the 1950s, so I guess it's just best to ignore anything from after Enterprise. It's legally not canon anyway since even the "Prime Timeline" elements from the new things are required to be at least "40% different" from the actual original universe.
Chris Chan's archenemies, The Private Villa of Corrupted Citizens, consisting of characters like Clyde Cash, Jimmy Hill, Billy Mays, Liquid Chris, The Man in The Pickle Suit, and Bluespike, among others, never did anything like this. The closest anyone ever got was when Bluespike convinced him to shove his medallion up his butt, and the other trolls all got very angry about it, with Clyde Cash himself telling Bluespike to stop, and then getting Bluespike to drop off the face of the earth. No, the people who turned Chris into a tranny and almost made him kill himself by slicing his taint open in an attempt to "free his inner vagina," those people were his "friends." They called themselves "The Teen Troon Squad," and were a literal gang of trannies. For all the horrible things the trolls did to Chris, it was nothing compared to what some tranny "friends" did to him.
The Last Stand is the one that wasn't directed by Singer, though. He left to do Superman Returns, where Lois cucks Cyclops with Superman.