I think that birds vary greatly, as far as personality is concerned. I have known many Rhode Island Reds, hens and roosters, and I have never known an aggressive one. I have had many, many New Hampshires and there too, they were always nice until I did get one aggressive male, but he wasn't too bad. In my experience my most aggressive male was a buff Wyandotte and that is not a breed known for aggression. I am an avid believer of keeping roosters with hens. I find their life more natural that way and the hens seem happier. I have a black Minorca rooster now who is somewhat aggressive. I have had many minorcas and he is the 2nd to be like that, while all the others, including my champion Mediterranean black Minorca, were really easy going birds. They were somewhat flightly, but the breed is not a calm breed. Hope this helps in understanding that chickens are really individuals. I believe the game birds are more aggressive, but look at the disgusting cruelty done to them when they are dubbed, having their combs cut off for style......because they used to be fighters before it became against the law......and that is horribly painful and cruel, no anesthesia is used. The APA still allows that by keeping it in the standard; it is truly sadistic and maybe that is why the birds get nasty...... Probably not, but it would be a good reason for it. Animal cruelty is always wrong.