Comment Flawed data to begin with. (Score 1) 981
What's misssing is the statistic that the child will actually be born intersex. He's using data assuming biological birth results in only male/female. I know it's nitpicky, but that's the whole point of the puzzle, to look past intuitive results.
The actual outcomes are
Boy/Boy
Boy/Girl
Girl/Boy
Girl/Girl
Boy/Intersex
Girl/Intersex
Intersex/Boy
Intersex/Girl
We can eliminate Girl/Girl, Girl/Intersex, Intersex/Girl. Someone else can figure out the math.