My dog just bit me on my hand.?

Your dog has a dominant issue. He sees himself as your pack leader, so when you touched his toy, he had to discipline you, which is a bite. Also, because he is the leader, he decides who gets close to you (his follower/the pack). When he does not want someone getting close, he growls to warn them and when they do not listen, he bites to get people to back away from you/the pack. And it does work because people back up. To fix this problem, you need to take the pack leader position from your dog. When you do so, your dog will become more social to people, like your brother, because you'll be able to let your dog know that your brother is okay to join the pack temporarily. Try reading "Be The Pack Leader" or "Cesar's Way" by Cesar Millan to learn more about the pack leader mentality and learn about the dog world and behavior. It is never too late to rehabilitate your dog; dogs live in the moment, they always let go of the past when you do. Good luck with your dog.