Cher had sex with Anthony Kiedis when he was just 13 years old. He revealed this interesting fact in an interview with Flair Magazine Italy. 

“My father asked her to be my babysitter, one night. She went in the bathroom to change. I was already a little curious, so I asked her if I was able to stay and watch her. Then, we went in my room and we had sex. I was 13.”  SOURCE