Magstphil, how do you get 5 girls??!?!?!?!?!? That is nuts. hehe.
To the OP, going back to what I said before, regardless of what sex your children are, if you have logical, sound, well-articulated arguments no one can say that you "don't know what you are talking about". Education is really where your credibility comes into play here. If you can knock them off their feet with what you know then they don't have the opportunity to discredit you, you will make too much sense.

That said, there are people who don't want your information, those irrational people simply can't be reasoned with. Don't feel bad if those people say lame things to you to put you off, deep down they know you are right.