Ex's Brother

I think I'm getting a crush on my ex's brother! I don't want to be mean by leading him on then realising I don't ACTUALLY like him so, how can I tell if it's him I like not just that he looks like his brother? Should I just give it time and get to know him better before jumping to the conclusion about my feelings?

I'd just steer clear of the situation myself. I did the sister thing... didn't end pretty.