I think this is related with the XY chromosome. Because you have the Y instead of the X you have a part where you don't have 2 genes to encode a feature. So the

I think this is related with the XY chromosome. Because you have the Y instead of the X you have a part where you don't have 2 genes to encode a feature. So there is not gen dominant and recessive. This leads a more variation when the Y is passed to the offspring. This is the example I read when I was reading about this: if the parents are X5X7 X6Y (where the number represents a feature that is not in the Y chromosome). The offspring could be X5Y X5X6 X7Y X7X6, but the feature is expressed as the average of the numbers: X5Y=5 X5X6=5,5 X7Y=7 X7X6=6,5. The women are more close to the average (6) than the men. Why is the feature expressed as the average? If one gene is recessive and another dominant only one matters. So it could be expressed like this: X5Y=5 X5X6=5 X7Y=7 X7X6= 7 where there are no differences between genders.