Gender identity is in the DNA. I didn't have to instruct my boys to like guns, swords, bows and arrows, dinosaurs, rough-housing, fistfights on TV, trucks, motorcycles, and military hardware.
If they didn't have a toy gun available when they wanted one, a peanutbutter sandwich or a chicken nugget with the corner bit-off would suffice in a pinch. They weren't forced to choose Power Rangers over Dora the Explorer, or Jurassic Park over Beauty and the Beast. They made those choices on their own.
Same with my daughters. They didn't need to be instructed to gravitate towards Barbies, Polly Pockets, and playing house. They weren't forced to choose Dora the Explorer over Power Rangers or Beauty and the Beast over Jurassic Park. They made those choices on their own.
Does it seem that once in a while, nature skews that somewhat? Yes, it does. My homosexual cousin Joe was an effeminate little boy from the time he could interact, and it became more pronounced as he grew older. My uncle could no more force him to "act like a man" and be interested in the things other little boys were interested in, than I could have been trying to force my boys to play with Barbies.
But to take an innocent child and attempt to "prove" your theory of blank-slate gender identity by f**king with their very lives is pure, unmitigated evil.