corn snakes can and do bite at all ages. They are not prone to biting alot, most tend to bluff before trying to bite, or do alot of mock bites (closed mouth strikes).
Hatchlings and wild caught corn snakes tend to be more nippy. Hatchlings instinctively feel everything is trying to eat them, hence they act completely defensive at any movement bigger than they are.
Does a baby hurt? If you even notice the bite...it doesn't hurt at all. Like tapping the blunt side of a pin.
Adult corn snake bites can hurt, they can bleed, but in general, they hurt about the same as a mosquito...just a bunch of them at once. Corn snakes have several rows of teeth on the upper and lower jaw curved towards the back to make it easer to pull prey into their throats and hang on. How painful it feels to you though, its hard to say. The strike is quick and more like a 'OUCH it bit me' and it doesn't hurt anymore..though you may bleed a bit from the bites. Just wash the injury, bandage up if necessary...worse thing that could happen is a bit of an infection due to one of the corn snake's teeth being stuck in your skin. Pop it out and a bit of antibiotic cream and you are all set.
Attached is a bite from a Texas Rat Snake...related to corn snakes (colurbids) and is actually a bit bigger overall in body length and thickness. This bite didn't hurt at all...it was actually amusing watching him working all those teeth into my arm for nearly a minute before he let go. If he had hit me on the fingers, he would have been able to get a more powerful bite...but even then I doubt it would have hurt much more. But it shows you nicely how the rows of teeth are arranged.

-----
PHLdyPayne