Do I add my son to my deed?

There's no reason to do that and there is some risk. You need to have a will anyways and adding them to the deed is unneccessary if you leave the house to them in your will. The risk is that if one or both of them have financial problems and get sued for debt, or they get sued for any other reason and a money judgment is entered against them, that's a lien on their portion of the house which will have to be paid upon sale or refinance of the property. The other risk is they would be free to convey their portion to whomever they choose. You may trust them completely, but you never know what might happen. Just because they reside there with you does not mean they have to be owners of the property.