I think people like to label and categorize things because it is just more comfortable, so this is this, and that is that. It will happen with siblings of any age, but when you have twins, they really begin to identify with it because they are always looking to find ways to individuate from each other. If one is labeled the shy one and the other is labeled the smart one, that becomes their identity. What I always try to do is say, in the presence of my kids, if someone says, "Oh, he's the shy one," or "He's so shy;" I will say, "Yes, he's being shy right now, but yesterday, you should have seen him. He is really funny and he was telling jokes and he's really outgoing." That way that our children know, whatever they are being labeled, is not their entire personality.