I think there is definately some heritability to attitude, but I also think there is a lot more to environment and how much you put into it than a lot of people want to believe. We know there are some genetic lines that just seem to produce cattle with a natural tendancy to be crazy, and some of them are just so crazy that they never settle down. But in 20 yrs I have seen very few cattle that couldnt be got to a manageable temperament with work.
In addition to me being all into the show world, my family also raises bucking stock! We wont keep a cow or bull that is dangerous! I know most people think bucking stock are just naturally mean, but most of our stock can be pet through the fence, and a lot of them will walk right up to you in the pasture for you to scratch their heads. The only reason we dont trust them all that much is some of them actually get a little pushy if you dont show them enough attention right away, and you just dont wont 2000 lbs of bucking bull pushing you around. We have a friend that raises some darn good bucking stock and everybody knows that whatever he brings to a rodeo is gonna snort in your shorts, and they are all out of bulls and cows that have the same attitude. Everybody, my family included, says they are proof that interaction doesnt settle them down, because he is out there with them every day. But here is my issue, he excercises these bulls every day(running bucking stock is very common to keep them in shape to buck), so these bulls interaction with him consists of him going out there using dogs to run em in the arena, using a hot shot to get em in the chute, and then using dogs to drive em a few laps around the arena. I think I would be mean to. All of his will come across the back 40 to get you, and everybody just thinks its in their genes. We have bought several bulls from him that had this attitude, and when they realize that we arent gonna manhandle em that way, and that a lot of days all we do is catch em up and feed em, every one of them has calmed down. They arent big babies, but they will walk right past me into the catch pen to eat, without even payng attention to me, and I can move em around in the catch pen without much trouble. They still get a little scary when you corner them and push em to hard, but any cow has the potential to do that.
SO I think genetics gives em higher potential but environment and how much and how you work with them has the most to do with it!