I would think its both,you could have a record breaking rack on a 150# deer,or a 400# 8 pointer that`s not all that impresive.What leads me to believe it`s more genetic that geographical is the fact that here in minnesota the record for wieght is 510#,now that lady that shot the 24 point -3rd biggest non-typical in mn. history wiegh 150# , at my cabin in 92 my cousin shot a 17 pointer that weighed 300 pounds, this is all over the board.IMO it`s genetics