I took a bath with my sister. She's starting to look a little more grown-up, but she's still a kid. Then she suddenly started to have an erotic vibe and we started hugging each other while kissing like adults! I was so fascinated by the difference that I lost all sense of reason and thrust hard into her vagina over and over again, cumming inside her many times! I was the only one who thought she was a kid, but my sister recognized me as a man. So when I touched her pussy, she was already soaking wet! Now my sister is my sex friend in the house!