Irish humor is an acquired taste, best acquired by birth. It’s no easy feat, arrogantly straddling the line between authenticity and tactlessness. Thus, an Irish comedy about an unwed mother in a chaotic, working-class family might not be everyone’s cup of tea. “The Snapper” (1993) is an amusing, upbeat film for the right audience. Colm Meaney is earnestly oblivious in helming his large brood, similar to the American dads of TV sitcoms. Tina Kellegher is the daughter whose pregnancy drives the story. She’s incorrigible enough to prevent the film from spiraling into dramedy territory, and we’re the better for it.