Ned (Paul Rudd), the title brother in Jesse Peretz's obnoxious comedy, does not qualify as an idiot so much as a passive-aggressive creep. Ostensibly a stoner with the philosophy that if you assume everyone is good they will rise to the occasion, he is inevitably taken advantage of by the unscrupulous. On the other hand, his "innocence" proves a trap for those who regard him as a sympathetic ear, because he invariably spills the beans at the worst moment. Despite that bad habit, when compared to his three sisters — Natalie (Zooey Deschanel) the promiscuous bad girl; Miranda (Elizabeth Banks), the ruthless career woman; and Liz (Emily Mortimer), the cheated-on housewife — he stands out as a paragon of wisdom and virtue. Homeless and bounced from one sister's house to the next, will Ned and his simplicity serve as a touchstone of truth for these miserable women? Dostoevsky's version was better, if not as funny.