I’ve heard rumors for years that Gillibrand’s mother was the mistress of Erastus Corning, who served 41 years as the mayor of Albany:
https://www.nytimes.com/2009/02/01/nyregion/01family.html
Her real name is Tina Kupnick.
Not a rumor, it is how she had the connections to launch her U.S. House career, and the state police report that leaked the call of Rep John Sweeney's drunken wife making false accusation on a 911 call.