Logical Thinking FAIL

I was walking around town and saw an oldish man (let's say 60's) with a young woman about my age pushing a stroller with a little kid in it (somewhere between 2-5 years old...that's as specific as I can get). While probably some sort of father-figure in the girl's life (cue Prince), I was wondering if the old dude could actually be her lover (shudder) and the father of the kid. So I decided to look at the kid and see if he had any of the man's traits. The first thing I looked for? Grey hair. I FAIL.