People tails

16 months old, and talking really well (full sentences). I was changing her diaper and she noticed a yarn toy on her changing table between her legs. She grabbed it and said "I have a tail." I told her that people don't have tails. She said "Daddy has a tail." At that time I didn't think much about it, till she caught my hubby getting out of the shower and she said (pointing to my husband's privates) - "Mommy, see there's Daddy's tail!"
I let her think that until my nephew was over about four months later and said "Look what I have!" She was like "why don't I have a tail!!"
I eventually told her the penis and vagina terms.