Would you think they are Pedophiles?

Statistically more men are involved in such things, so yes anyone would be more cautious of them. You'd have to either be the worst parent/sibling ever or kidding yourself to think differently. There are dangerous women, and yes you should always watch your kids anyway, but if you're at a park with your kid and a woman approaches it's most likely because of mothering instincts and overall friendliness.

"Stereotypes" happen for a reason. There's no real point or revelation being made in this thread. It's unfortunate if you just want to be a friendly guy but I dunno... even that is kind of weird. There are ways to be nice to kids without seeming like a total creep, too.

edit: and no you should never think anyone is a pedophile for no reason, you should be cautious of everyone of them and keep a reasonable amount of doubt at all times.