Brad (Will Ferrell) is a stepfather. But what he truly wants to be is a dad. The difference between a dad and father, explained at the very beginning of the movie, is that any guy can be a father but being a dad is about parenting. So he slogs it out to pack lunchboxes for the kids of his wife (Linda Cardellini), takes them to aquariums, and cheerfully puts up with their drawings depicting him as a corpse or with poop on his head.
Entering the picture is the real father Dusty (Mark Wahlberg), the diagonal opposite of the meat-and-potatoes variety of dad that Brad is. Dusty is s....