Story highlights Kim Jong Un married his wife Ri Sol Ju in 2009

Very little is known about their children or private life

Seoul (CNN) North Korean dictator Kim Jong Un has a third child, South Korea's National Intelligence Service (NIS) has learned.

Lawmakers were briefed on the matter Monday, said Kim Byung-kee of South Korea's ruling Democratic Party, though Kim Jong Un's wife Ri Sol Ju is believed to have given birth in February.

"The gender of their new child is unknown," the lawmaker said.

Little is known about the North Korean first family, but Kim said he learned from "non-NIS sources" the couple's first child was a boy, born in 2010, while the second was a daughter, born in 2013.

Opposition lawmaker Yi Wan-yong said "Kim's first child is a son and the second child is a daughter," noting he also learned this information from non-NIS sources.