I couldn’t stand “The War With Grandpa,” but this is probably a good place to mention I’ve never liked “Home Alone,” either.

Like “Home,” “Grandpa” is a hurting-each-other comedy about the feud that develops when crotchety Grandpa Ed (Robert De Niro) moves in with his daughter (Uma Thurman) and her family, displacing grandson Peter (Oakes Fegley, from “Pete’s Dragon”). The kid doesn’t like being shifted to the attic, despite the attic being objectively cooler than his old room, and so the two one-up each other with pranks that start at uncomfortable and escalate to bordering on grievous bodily harm.

“Grandpa” shifts between the cohorts of the two characters, with Peter’s scenes playing out like your average middle-school gross-out comedy and Ed’s like all of those Morgan Freeman/Alan Arkin/Michael Douglas coot comedies where the guys talk about their prostates while playing golf. It plays out almost as if it were two different movies shoved together, which makes it difficult to discern whom this try-to-please-everyone comedy is intended for: aging third-graders? Undiscerning seniors?

In an overqualified cast that includes Christopher Walken as Ed’s pal and Jane Seymour as a big-box cashier who becomes his love interest, Thurman comes off best because her character doesn’t get involved in the shenanigans that peak (weirdly early) in a dodgeball game. Mostly, Thurman is called upon to react with either bemusement or mild horror to the generations between which she is sandwiched, and she does it with aplomb.

Thurman aside, the humor in Tom J. Astle and Matt Ember’s script is mostly insult-based, like a subpar episode of TV’s “The Goldbergs.” That’s too bad because “Grandpa” wastes a potentially interesting situation, one which is happening around the world as more extended families set up house together.

It’s surprising how much nudity there is for De Niro’s body double, especially in a PG movie. But the rest of “Grandpa” would be entirely predictable even if the strings on the soundtrack in the opening scenes weren’t already preparing us for a heartwarming conclusion. As a result, the “War” of the title ends up not being about who’s going to get the bedroom but who’s a viler character.

The kid is mean and disrespectful from the get-go, so he’s the early leader in that battle, but eventually Ed admits, “I’m the grown-up and I ought to have known better.” Amen to that. And if he had known better, it would have saved everyone a lot of annoyance.