At least according to The Economist.
I'd go with great grand dad. But otherwise I agree.
Link: https://www.economist.com/briefing/2020/07/04/joe-biden-has-a-good-chance-of-becoming-a-surprisingly-activist-president?fsrc=scn/fb/te/bl/ed/americasextraordinaryelectionjoebidenhasagoodchanceofbecomingasurprisinglyactivistpresidentbriefing&fbclid=IwAR3mk