American Outsiders in the short story: What have you done?

Pretty much liked at least admired Ben Marcus's story "What have you Done?" in current New Yorker - don't know too much about Marcus but believe he's a Brown grad, first novel or collection a bit post-modern/experimental, like the first fiction of many writers, especially Brown grads, and now, like most maturing writers, he seems to be edging closer to the mainstream. This story - I think it's a story, though it could be part of a longer work - fits tightly in with the long American tradition of stories about loners and losers - so much of American literature is about the aliens and the misfit outlaws, but in novels they tend generally to be more heroic (even comic-heroic, as in Confederacy of Dunces) whereas in short stories they tend to be just plain outside the pale. Marcus's hero is a 30ish guy heading back to family in Cleveland for some kind of family reunion. Evidently he has not been back to home town in many years, and also we learn right away that there are extremely disturbed and troubled relations between him and his kin - it's entirely clear why that is, but it is clear that young man is a great life and career disappointment and that he is perhaps prone to fits of violent rage, clearly a troubled young man who is bitter and cynical. Marcus goes out of his way to make this character dislikable and pathetic: emphasizing the grotesque (his overweight body, his body stench), the juvenile sexuality (as soon as he gets home he downloads some porno and masturbates), his fixation on his sister's sexual life, and so on. What's really the oddity in this story, however, is that we learn quite a ways in that the character is married and has a son - he has never told his family this. When he does, they don't believe him, they assume it's another one of his pathetic attempts to fit into their expectations by lying to them. Is this credible? I suppose anything can happen, but it's hard for me to believe that someone could or would keep this secret from parents/sibling whom he has any relationship with whatever, whom he has any desire to please. It's that contradiction at the crux of this story: character's need to please his family but unwillingness to reveal to them, over a long period of time, the one thing that would best enable him to do so, that puzzles me and makes the story feel more like a set-up, either the author's concoction to build drama and mystery or something pointing toward a larger work that will explain this anomaly. Quibbles aside, the writing is very strong, the descriptions of Cleveland, the airport, the hotel where the family holds its reunion; some of the dialog, painfully cruel, also seems very smart and apt.