Get his mum an apprentice. At first she'll be really miffed with you, and give the young'un a detailed unflattering verbal genetic description, and maybe even a swat. (I once had a senior cat regularly go into my closet and tell her troubles to an old rabbit fur coat.) Then she'll give him a quick and reluctant lick/wash when she thinks nobody's looking. Then acceptance, then playing. It'll be good for you, too. And for the kitten, especially if you get the one your instincts lead you to at the animal shelter.