Is Tom sociable with other cats? Usually the advice is to get a kitten of the opposite sex to your current cat. Having said that we have five cats, four boys and one girl and she dislikes two of the boys and the feeling is mutual.
Our most recent kitten from August last year is a boy. We thought it wouldn't be an issue as our youngest cat at the time was very friendly and sociable. Youngest cat took the new kitten as a deeply personal insult for four days. Total diva meowing and huffing about the place. The kitten was bemused but very polite and kept out of his way. On the fifth day the youngest cat discovered that the kitten was playful and they've been best friends ever since.
There's no way of knowing in advance how it'll work out. Over many years I've had more successful pairings than unsuccessful. Good luck.