The Tyra Banks Show The Tyra Banks Show

Alaska Gov. Sarah Palin had a good idea her teenage daughter was having sex, according to Bristol Palin's former fiancé and babydaddy.

"I'm pretty sure she probably knew," 19-year-old Levi Johnston said during an appearance on The Tyra Banks Show (scheduled to air April 6). "Moms are pretty smart."

He said the young couple practiced safe sex "most of the time," and he was allowed to share a room with his high school sweetheart in the governor's home.

Bristol Palin, 18, and Johnston welcomed their son, Tripp Easton Mitchell, on Dec. 27. They called off their engagement in March.

"Bristol did not even know Levi was going on the show," read a statement from the family's rep, according to People. "We're disappointed that Levi and his family, in a quest for fame, attention, and fortune, are engaging in flat-out lies, gross exaggeration, and even distortion of their relationship."

Johnston was joined on the show by his mother, Sherry, and sister, Mercede, who talked about being silenced during Sarah Palin's bid for the White House.

"We were supposed to say that all questions need be brought up to the McCain campaign," said Mercede. "Other than that we had to say no comment."

Palin has been named as a likely Republican presidential candidate in 2012.