From the experience, milk (quality and quantity) helps to show the potential of the calf from the start. If there is some lack of it the calf won't show it's potential until proper nutrition will be given. The same thing works the opposite way. If there are no good genetics, but cow provides good nutrition, the calf might grow well and be in good condition, but the muscle definition is genetical thing. Nutrition just helps it be more or less well developed.
This cow has plenty of milk, but the quality also should be great. Her whole family females raise great calves.