Nancy’s husband Paul Pelosi’s brother Ron was once married to and divorced from Gavin’s aunt Belinda (Gavin’s father’s sister).
Source: Belinda Newsom obit:
https://www.sfgate.com/bayarea/article/Belinda-Barbara-Newsom-dies-at-73-3183702.php
In short, for ten years of his (1967-77), Gavin was related to Nancy by marriage. However, by no one’s standard meaning of “aunt/nephew” would Nancy be considered Gavin’s “aunt.” For a decade, Ron Pelosi was Gavin’s uncle by marriage, but his brother Paul not not have been considered an uncle to Gavin, nor would Paul’s wife Nancy have been considered an aunt.
“Nancy’s husband Paul Pelosi’s brother Ron was once married to and divorced from Gavin’s aunt Belinda (Gavin’s father’s sister.”
Wowzer; makes my head spin trying to connect all the dots.