Babies’ little bodies can do some pretty amazing — and sometimes confusing — things. That precious smile? There’s a good chance that’s gas. And the way the baby grasps your finger in its palm may seem like you’ve instantly developed some type of deep connection, and while that might be true, it’s likely a reflex. So if you see your baby lounging on their back, appearing as though they’re about to grab a bayonet and become the fourth musketeer, you may leap to the assumption that they’re some type of fencing prodigy. (Think of those college scholarships!) We hate to be the bearers of bad news, but that’s a reflex, too. Specifically, tonic neck reflex, which comes in two varieties: asymmetrical and symmetrical. Here’s what to know about each.