Parents and Children in films

[AleisterCrowley]

Er... Laura Dern has been in at least one with her mum, and possibly dad (Bruce)

[Itsallaguess]

Not parent/child, but in terms of siblings in the same film, you'll struggle to beat The Long Riders -

The Long Riders is a notable film in part due to the decision to cast four sets of actor brothers as the real-life sets of brothers:

The Keaches : Jesse James (James Keach) and Frank James (Stacy Keach)
The Carradines : Cole Younger (David Carradine), Jim Younger (Keith Carradine) and Bob Younger (Robert Carradine)
The Quaids : Ed Miller (Dennis Quaid) and Clell Miller (Randy Quaid)
The Guests : Charley Ford (Christopher Guest) and Robert Ford (Nicholas Guest)

It also features an uncredited appearance by Ever Carradine, daughter of Robert Carradine and niece to David and Keith Carradine. Additionally James Keach's son, Kalen Keach, is cast as Jesse James's son Jesse E. James. Savannah Smith Boucher played Jesse James' wife, Zee.

https://en.wikipedia.org/wiki/The_Long_Riders#Cast

One of the most famous parent/child performances would have to be On Golden Pond, with Henry and Jane Fonda.

Cheers,

Itsallaguess

[kempiejon]

Ryan and Tatum O'Neal - Paper Moon https://www.imdb.com/title/tt0070510/

[gvonge]

Charlie and Geraldine Chaplin - Limelight