Mark Wahlberg and Will Ferrell go at it again in “Daddy’s Home,” a bio-dad vs. stepdad romp that rarely romps, despite the considerable comic chops of the two leads.

Ferrell is the hovering, nurturing step dad to two tykes whose mother (Linda Cardellini of TV’s “Mad Men” and “New Girl”) he married.

Brad is all about the tucking in, the volunteering at school and singing the praises of his practical Sport Maternity Vehicle (a Ford Flex).

The kids’ often-absent “real dad” is named Dusty (Wahlberg). Tough, menacing and sexy, he’s “like Jesse James and Mick Jagger had a baby!” And he’s angling to get back into his kids’ lives and his ex-wife’s bed.

Not that he comes right out and says so. He flatters, disarms, and THEN attacks. Brad has “cracked the code,” so much respect he says. Only respect is the last thing on Dusty’s mind.

Brad tries not to let Dusty’s pushiness, his rudeness and his gamesmanship rattle him. He’s just “a rascal.” All Brad needs to do (according to “Step into Step Fathering,” his self-help book) is “set up a loving fence.” Create some boundaries, preferably ones that Dusty won’t roll over like Putin in Crimea.

The conflicts here are obvious, the bones of contention even more so. Brad advocates a non-violent approach to bullies. Dusty?

“Check your history books. Almost everything is solved by violence.”

The reality of the set-up — kids who don’t respect “not my real dad” — is undercut by patently ridiculous scenes. Dusty comes along to the fertility clinic where his doctor pal (Bobby Cannavale) might help the less masculine Brad procreate?

But Thomas Haden Church scores some funny lines as Brad’s boss at the “Smooth Jazz” station where they work.

Director Sean Anders (“We’re the Millers,” “Horrible Bosses 2”) is satisfied letting this play out by rote, a comedy whose laughs are more irritating than anything else. You feel sorry for Ferrell’s character, then Ferrell himself. He still can deliver, but this script is watered-down lite beer.

Watch for the Go Pro skateboarding half-pipe scene for the movie’s one clever visual touch, an effect that looks pasted-together on Youtube.

The dead spots — and there are many — let you wonder if this might have worked had they tried what Fey and Poehler did in “Sisters,” playing against type. Make Ferrell the butch tough guy and Wahlberg the wuss.

By playing it too safe, “Daddy’s Home” never finds that comic sweet spot and never rises above, “Well, it’s not awful.”

MPAA Rating:PG-13 for thematic elements, crude and suggestive material and for language.

Cast: Will Ferrell, Mark Wahlberg, Linda Cardellini, Thomas Haden Church
Credits: Directed by Sean Anders, script by Sean Anders, Brian Burns and John Morris. A Paramount release.

Running time: 1:36