Justin Bieber's mum hasn't had sex in 16 years.

Pattie Mallette was 21 when she vowed not to have sex again until she was married.

Now 37, the famous mum, who was 19 when Bieber was born, says, "I take that vow really seriously. I remember when I made it. I wrote it down on a piece of paper and I had someone witness it. It means a lot. I made it this far. I'm not stopping now."

In a pre-taped Tv interview with Ellen DeGeneres, which airs in America on Tuesday (18Sep12), Mallett reveals she isn't even dating at present, telling the host, "I told Justin I would focus on him and would wait until he was 18 before I started dating... He just turned 18."

Making light of her guest's love life, DeGeneres offered Mallette a six month subscription to dating website Match.com.