First of all, why would your Step Mom say such a thing. Has your cat been acting sick ? If you have any concerns, I'd go to a vet and have him tested. Even some local animal shelters will do testing for the public and much cheaper than a vets office... Yes there is such a thing as FIV, and its a terminal illness that can be passed to other cats... FYI.. my experience working at animal shelters has taught me one thing. Vet Techs have a little bit of knowledge, and like they say, "A Little Bit of Knowledge Is Dangerous" ok ok, all you vet techs out there are gonna be mad for that remark, but I stand by my observations...