The latest breakthrough in the burgeoning field of birth-order research reveals that parents discipline older kids much more severely than the younger ones. My own thoroughly unscientific poll also finds that this experience is common: Four out of five friends felt that hell yeah, younger siblings got away with murder. Well, not murder per se, but other transgressions such as sneaking home at 5 AM, shoplifting car stereos from Caldor, and smearing Vaseline on the family toilet seat.