The Tremors actor has been married to the Closer actress for 23 years, and have two children, son Travis, 22 and daughter Sosie, 19.
The pair found out that they are distant cousins while appearing on genealogy show Finding Your Roots.
Harvard professor Henry Louis Gates Jr, who presents the series, confirmed that they are "indeed distant cousins".
Referring to the celebrity connection game 'Six Degrees of Kevin Bacon', he added: "So talk about six degrees of separation, right?"
On what he hopes the new series can provide, he added to Zap2It: "I want... Americans [to] realise how united we are as a people.
"There's so much animosity... and one of the things that I want the series to do is to show that, deep down, we are all Americans. We've been sleeping together from the very beginning of the country."
Kevin Bacon will star as the "good guy" in Kevin Williamson's new serial killer pilot from CBS.
> Kevin Bacon: 'Dirty sex saves marriages'
Finding Your Roots airs on Sundays at 8pm ET on PBS.