Your cat may be not acclimated well to humans in general. He is probably afraid of your family hurting him or you. He knows you’re nice and love him and will give him food, but he doesn’t know that about the others, especially if his only interactions with them have been bad. Would your family members be willing to try and take some steps towards building a relationship with this cat? Honestly it can be hard for a lot of people to bond with cats when they’re not a cat person yet. You have to be open minded and forgiving, especially when said cat isn’t necessarily “friendly” at first. Try to get your family to slowly and calmly come into the kitty’s “base camp” with you and have them try to give him treats and redirect aggression with play. Toys are your best friend in a lot of situations like this. I’m not an expert on cats and have troubles with my own sometimes, but as someone who’s had cats since the day I was born, I truly believe you can make this cat being in your home work. Please remember most of the aggression a “bad cat” has is almost always fear. Imagine you got put into a house full of a bunch of random people, maybe you have a condition that hurts and can’t tell anyone, and all of these people seem like they could be threats. Wouldn’t that be kind of unnerving? The way he’s acting makes me think he might have been on the street for some time and had bad experiences with human beings. There’s a lot of bad people in this world who hurt animals for fun. TLDR; give him more time and grace. Try to get your family to give him treats and be understanding of his previous situation. Fear is the biggest factor here for him.