Originally Posted by Pedestrian

I see.

The question we're being asked is about the odds of two disjoint events occurring together (Girl 1 followed by Girl 2), not the probability of a single event (the birth of either a boy or a girl).

I'm not sure if we can assume that biologically, inheritance of the X or Y is an even 50/50 split, since more women are born in the world than men, but I see where this is going.