We have one of each. Mary Joyce never would let us rock her to sleep completely. She likes to cuddle at night, and we rock and read books and sing songs, but she has always gone to sleep on her own. As much as we wanted to rock her to sleep, it just never worked. Katherine, on the other hand, is a rock-to-sleep girl. She falls asleep every night in my lap or her daddy's, and that's the way it has always been with her. She'll be 11 months old this weekend.