We need more movies about dysfunctional families like we need more movies about the tortured inner lives of artists, which is all the more reason to be unexpectedly grateful for “The Family Fang,” a sharply drawn portrait of a dysfunctional, tortured artistic family that speaks affectingly to the troubled legacy that all parents inevitably bequeath to their children. Following his raucous and foul-mouthed directorial debut, “Bad Words,” Jason Bateman shows marked progress and deepening maturity as a filmmaker with this cleverly structured but never arch or mechanical adaptation of Kevin Wilson’s 2011 comic novel, with Bateman and Nicole Kidman nicely inhabiting one of the more tender and persuasive brother-sister relationships in recent movie memory. With its rich vein of melancholy and intricate but entirely accessible narrative layers this is a triumph.