Levi Johnston: "Pretty Sure" Sarah Palin Knew Of Sex Going On Under Her Roof

Levi Johnston, the teenage father of Sarah Palin's granddaughter, said the former vice presidential candidate let daughter Bristol share a room with him at their Alaskan home, knowing they were probably having sex.

"I'm pretty sure she probably knew," Johnston, who admitted there were times the couple didn't use protection, told Tyra Banks in a segment on her show slated to air Monday. "Moms are pretty smart."

The couple's child, Tripp Easton Mitchell, was born Dec. 27, 2008; Bristol Palin told the AP she was "devastated" when the couple split up last month, while Levi hinted of a future reconciliation to ABC news last month.

Johnston was prominently featured onstage during last year's Republican National Convention.

Johnston's sister, Mercede, told Banks the family was under a gag-order throughout the campaign, instructed only to answer questions with "no comment."

(Photo: Warner Bros./Karl Giant)