Do I have to leave something to each of my children in my will? It's not that I don't love my son dearly, it's just that I've already put him through medical school and bailed him out of financial troubles a few times. I'd rather see my money go to my daughter, who has never asked for any help.
Now that he's grown, you don't have to leave your son a darn thing. Death is our late but great chance to mete out a little justice in the world -- reward those who served us well, punish those who served us ill, and make sure someone feeds our cats. If you're reluctant to break your decision to your son now, you could save it for your eloquent deathbed speech or, better yet, attach a letter to your will.
Make sure, however, that your will clearly states your intention to leave your son nothing. Most states have laws that protect against accidental disinheritance, and your son could potentially use one of these to challenge your will in court.
Had your son still been a young child, the rules might have been different. Some states' laws give inheritance rights to minor children. The Florida constitution, for example, says that your spouse or minor child gets first dibs on the house, no matter who you try to give it to in your will. Unless your son is a child genius, it sounds like he is old enough to put a roof over his own head.
For more information, see Inheritance Rights.