Sometimes, genealogy can be used not only to prove family relationships, but also to disprove it. If you follow California wing nuts you have no doubt heard that our governor Gavin Newsom is Speaker Nancy Pelosi’s nephew. Uh, no. He’s not. Here’s the scoop. Gavin Christopher Newsom was born in 1967 to William Alfred Newsom III and Tessa Thomas Menzies Newsom. Bill Newsom had a sister Belinda, who in 1960 married one Ronald Pelosi.