Thinking about breeding my horse?

I've been really thinking lately about breeding my horse. She is a 5 year old Quarter Horse mare with pleasure bred bloodlines. The only thing I'm stumped on is her temperament. She can be a bit spooky at times and I wonder if there is a slight chance the foal will turn out that way too. Her half brother acts the same way so I'm wondering if it was their sires that they got it from. I have my mare's mother and on a scale from 1-10 (1 being calm 10 being spirited) she is a 1. So can traits like that be ped on?