Any truth behind Skull theory?

As above..
Is there any truth to the skull theory or is it Nub all the way??
Flatter skull girl?
Rounder boy?
whats earlies you can generally tell for both week wise / scan wise?
Thanks

Nub definitely over skull, skull is just for fun guessing:) Do you have any pics you can post for us :)

There is a little something to it but it's a lot easier to tell WITHIN the same family than across families. Like, my daughter's skull was def. different than my boys, but across families there's so much variation it's hard to tell.