Why am I more inclined to have a son?

My only requirement for a boy is that he stays alive; even working in a factory screwing bolts is fine.
Everyone has their own fate. Whether he's successful or not often has little to do with his personal abilities—it's about the times—so I can be quite at ease.
If I have a daughter, I’d probably turn into a worrying mother.
I'd be constantly anxious and concerned, even on the day I die I'd still be calculating whether the insurance and assets I leave for her will be enough for her to live to 100.