Plenty normal! I had a daughter was always 'at it' - and a son who was not interested in his penis at all! I have a 2yr old son now ....we'll see how he does....
My daughter probably started later on - i remember when she was 5 and first rode a horse, she came home and rode the furniture for weeks! I do remember confiding in a friend and she said her daughter - at like 18 months was humping things - especially the little bath ring (this is more than 15 years ago) that had a piece that came up between her legs.
i definitely think its normal....much as i cringed when it happened....gotta say its normal. Everyone expects it from the boys, turn about's fair play!
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