I don't know whether or not disposition/attitude/aggresiveness is something that is passed on or learned from but out of about 100 roos - I've only had one mean aggressive one and it was one of the nicest looking of the original BCM flock I bought. He was one of their offspring and still sort of young and I was warned that he was "mean". Well he got meaner and meaner. I couldn't go in the pen to get the waterer without him attacking me. He would attack anyone who got near that pen. We had a young high school girl working for us for the summer (last year) and I had to warn her not to go in that pen. DH couldn't do anything with him either. He got so bad we were kicking the breath out of him and he would still get up and attack you - and I mean full Ninja flogging, spurs, ride your back, jump on your face and claw your eyes out kind of stuff.
I tried all the things I've read here - carry him around, etc. etc. I carried him around all right - carried him upside down threatening to swing him against a tree if he didn't stop.
Okay, don't go all PETA on me.
Nothing worked.
So I turned him loose. Took him out of the pen thinking he would be better if out, totally free, with all the other non-breeder hens/roos running around here. Figured it was a protective of his pen kind of thing. Well....I was really, really wrong. At least when he was in the pen I knew where he was and could prepare myself (rake in hand). Once he was loose it was like a WAR every day with some enemy hiding in wait for me. He would hide under bushes, behind coops, barns - you never knew where he would be - but suddenly he's on me, trying to kill me. He would chase me all over the farm.
Finally, one day, I came in and told my husband "That roo has just volunteered to be Sunday dinner for the last time" - so.....we honored his final request.
I have a farm that is open for tours. No way, no how can I have an aggressive animal of any sort running around here. Plus, I have new grandbabies that will be learning to walk and explore the farm. I just won't risk a rooster with an attitude - not even in a pen because I saw how dangerous he could get.