Jonas and Wyatt Maines were born identical twins, but from the start each had a distinct personality.

Jonas was all boy. He loved Spiderman, action figures, pirates, and swords.

Wyatt favored pink tutus and beads. At 4, he insisted on a Barbie birthday cake and had a thing for mermaids. On Halloween, Jonas was Buzz Lightyear. Wyatt wanted to be a princess; his mother compromised on a prince costume.

Once, when Wyatt appeared in a sequin shirt and his mother’s heels, his father said: “You don’t want to wear that.’’

“Yes, I do,’’ Wyatt replied.

“Dad, you might as well face it,’’ Wayne recalls Jonas saying. “You have a son and a daughter.’’

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“Even when we did all the boy events to see if she would ‘conform,’ she would just put her shirt on her head as hair, strap on some heels and join in,’’ Kelly says. “It wasn’t really a matter of encouraging her to be a boy or a girl. That came about naturally.’’

Kelly and Wayne didn’t look at it as a choice their child was making.

“She really is a girl,’’ Kelly says, “a girl born with a birth defect. That’s how she looks at it.’’

Seems like this person, who was physically a boy and treated as a boy and pushed into conforming as a boy, felt like a girl the whole time. Seems hard to argue that's a social construction (nurture) and not an innate characteristic (nature). Via Led by the child who simply knew - The Boston Globe.