Do you tell your son that he is too? Do you talk about their strength, or intelligence or humour? Is there a difference in how you talk to your boy or girl children on these other traits?
I think this is the key. I cringe when DD gets girl-specific praise, or even gets told what a "good girl" she is. Stereotyping goes so far beyond us as parents, and I think we're silly to try and stop it ourselves. Better to help kids think for themselves and understand it, so as to be able to see through it, rather than be blinded by it.