We have several females well over 4000 grams and a few that are over 5000. I disagree that size is not genetic. I believe it can be by evidence of some of my Pied and het Pied animals. My largest girl being a 5500 gram het Pied and several of her offspring in the 3500-4000 gram range. I agree, the Volta animals are probably just old, well-fed adults.