The author is yet another science denier.  

While I don't doubt that he/she feels like a woman trapped in a man's body (for that there actually is some legitimate scientific evidence); promulgating the nonsense that gender is completely independent of biological sex is another matter entirely. 

Essentially, it's the nature vs nurture argument being claimed as fact against incontrovertible evidence to the contrary, across all cultures and geographies. 

Insofar as nature vs nurture for a kid's success later in life, that is far from absolute, and in any event, their genetics do inform the outcome, just not all of it.