She explained: "We've got other people to think about. My brother's got three kids. Do we want that life for them without them being old enough to choose if they want to do it or not like my brother and I were."
Kelly was just 15 years old when the show launched on MTV and, although it only ran from 2002 until 2005, she couldn't believe how successful it was with viewers.
She said: "The first season was such a magical time in my family's life because we had no idea what we were doing. We had no idea that the show would be so successful. When I signed the contract for MTV, I was 15 years old and to see what it turned into, we didn't know how people would perceive us or anything.
"And then suddenly wake up one day and literally be one of the most famous 16-year-olds in the world just being yourself.
"I think that is the most raw and vulnerable you will see any family on TV. And then it all kind of was like an explosion of too much reality for us."