I have recently adopted a hound mix named Charlie. A coworker of mine was fostering him and before I adopted him she made it clear that he was kind of aggressive and had issues with men and children. He has been nothing but sweet to me and he generally likes my roommates but if they start waving their arms around or something he starts to growl. My brother walked up to my car to see him right after I got him and Charlie tried to bite him and the same happened with my dad. It only seems to be certain people though. This morning I was walking him and a neighbor asked to pet him and I said no, it's not a good idea considering Charlie already had his teeth bared and was growling but the man didn't listen and reached for him and Charlie lunged at him but I pulled him back with the leash. Is there any way to change this behavior? I don't want a child or somebody to be unnecessarily bitten. Especially my dad and brother.