Im sure its environmental too, as we re-homed a free-range cockeral (OEPF) as he was getting severely beaten up by our ex-commercial hens as he was so timid, he ended up hiding under thencars 24/7. in his new home he got very aggressive and would attack anyone in his pen.
i wouldnt tolerate a free range cockeral with kids/public around if he is aggressive as it only take one kick to scratch a kids eye. pen him or pot him.