In my experience it's down to the individual bird. I've kept or known of the following breeds with really nasty cockerels: Lemon Cuckoo Orpington, Wyandotte, Marans, Barnevelder, Brahma ..... Our current Silver Grey Dorking cockerels are all very laid back and the Speckled Sussex is a real softie. We have one Dorking available - whereabouts are you?