My male cat trying to mate with spayed female

Question
why is my male trying to mate with my fixed female? They are a year old and brother and sister. He is tormenting her.

Answer
Janice,

Is the boy neutered?

If not, he needs to be.  Whole males will often try to breed with anybody.  This is the height of breeding season in the Northern hemisphere, so whole males get even more sexually active than usual.

If he is neutered, you might have him checked by your vet to see if the hormone levels are correct. If they are too high, than he might need some short term hormone therapy. Right now, as I said before, it is the height of breeding season and even neutered males sometimes want to get in on the act.

Please let me know what develops.

Best regards... Norm.