Wilson's brother Brian has shared the baby news in a post on Twitter.com, revealing his nephew Michael and his wife Samantha are new parents.
Brian Wilson wrote, “#DennisWilson son Michael & his wife Samantha welcomed their new son Dennis into the world yesterday - 30th anniversary of Dennis’ death.”
Dennis Wilson drowned off the coast of Los Angeles on 28 December, 1983.
His son Michael, is a child of his second marriage to Barbara Charren.
The baby news comes just weeks after filmmakers hoping to turn Wilson's life and death into a new movie, starring Aaron Eckhart, scrapped the project.