Why are men so over protective and call women sisterwhen they arent related?

It's kind of a primal instinct. Men like to think they're dominant and that women belong to them; it goes back to the cavemen days (literally; it's impressed in our psyches) when men had to protect their "herds" of women and children. As for calling us "sister", that could be either a form of affection or they're trying to annoy you. Could go both ways here.