Right now, our oldest son has four daughters and our second-born has one small son. So we told our middle son that he and his wife will always have the distinction of being the first in our family to have children of both sexes (something my husband and I know nothing about, having raised only boys). As everything was (is?) a competition in our all-boy house, he can claim that he's the winner at breaking that particular barrier. His brothers may do it in the years to come, but he will always be the first.
It will be fun to watch yet another of our sons who grew up without sisters interact with his little girl.
So far, it appears to be a love match.
When I think of son #3 now, this saying comes to mind:
He will be G-Man's hero (I daresay he already is); and though she may grow up and find her own Prince Charming some day, he will always be Princesa's first love.