Louise Simonson (signed for 2012 Upper Deck Marvel Beginnings Series III) was married to Jeffrey Catherine Jones (signed for Star Wars Galaxy and FPG Jeffrey Jones) when he was a dude; later divorced him and married Walt Simonson (signed for 2008 UD Marvel Masterpieces 3).

Wikipedia says that Helena Bonham-Carter (signed Harry Potter) and Crispin Bonham-Carter (signed James Bond) are distant cousins. Helena has shacked up with both Kenneth Branagh (Thor, Harry Potter) and Tim Burton (Nightmare Before Christmas).

Jack Quaid (Hunger Games)
Meg Ryan - his mom (Leaf Metal Pop Century)
Randy Quaid - his uncle (Leaf Metal Pop Century)

Here's one I found in my binders but didn't know there was a relationship until I looked.

Jim Belushi in Twin Peaks and, not brother John, but son Robert Belushi in Agents of S.H.I.E.L.D.

I don't really collect pack-issued autographed cards, but I do send a lot of cards off in the mail with requests to the actors to sign them. Robert Belushi is someone I'd try and get a signature of, but he only appears on pre-signed pack-issued autographed cards -- no "base" cards.