Do you think bad tempers are hereditary?

Only, I've got a vicious bloody temper on me, at times, me dad's is worse, me mum's is even worse still, and me kid sister's is the worst out of all of us. Me nan, (on me mum's side), was as placid as anything, but me grandad, (again, on me mum's side), had a VILE temper on him, and a VERY short fuse. One of me aunts, (on me dad's side), is, once again, as placid as anything, but, apparently, (like me dad), apparently, all of me uncles on HIS side've got nasty tempers on 'em. My question to you guys is, do you think bad tempers are hereditary or what? Have YOU noticed a pattern for 'em in YOUR family? I'd REALLY appreciate YOUR angles on this one, please, guys. Much obliged! Peace and love! Be lucky! :)