From my experience, mother and son can enjoy a relaxed and satisfying sexual relationship. A key is to groom the boy from an early age (bathing him or cuddles in bed - let his erection be natural, let him explore your body), don't ambush him when he's a teenager, that could get weird for him and tragic for you. It's also important to keep servicing your husband sex - you really don't want that sort of jealousy in a family. So long as hubby is getting plenty of your sexual favour and he doesn't feel threatened then, they're usually OK