Lil Wayne has four kids. Three sons and a daughter by four different women. Officially.

But Weezy may have another son. A 15-year old boy with Keiotia Watson, who claims Wayne had a sexual relationship with her in June of 2001.

She named the boy Dwayne, after Wayne's real first name, and two years ago she went to court to establish paternity. A Lousiana judge agreed she had a case and ordered Wayne to pay her 5K a month in child support.

Only Wayne didn't. His peeps say it was because he was never served any legal papers suggesting he was a daddy for the fifth time

The situation has come to a head, and sources tell TMZ that Wayne is about to take a paternity test. If he turns out to be the dad he's expected to do the right thing and pay up.

[Related: Lil Wayne's daughter calls out T.I. for attention seeking.]