@Sage04 My grandson is going into college and, he, too, was never told anything about this. If I didn't bring the subject up, he wouldn't have been aware of it.
I did go to the Selective Service website and they are very clear that there are possible criminal penalties for not registering; also some job opportunities and/or student loans that might be denied him now and in the future.
I'll discuss this with my daughter (his mother) and hear what she has to say; however, I think he should register now that he's aware that it is the law.
P.S. There are exemptions from registering; however, he does not fall into any of those categories.