This is very interesting. In reality this shows the cross within litters, lines, and families genetically. If you want to maintain a line off a male you would inbreed and keep sons or line breed and do the same to stack the y chromosomes. It's really not taking away from the males it's just adding more precision and perspective to breeding. Male and female equally give 39 chromosomes but with the larger X chromosone in females. The Y chromosomes of males carry less INHERITABLE MATERIALS.This makes picking a female very important. It shows why picking a solid family or line is important rather than just breeding peds. It seems after reading autosomes the other 37 chromosomes influence features. With just this info it's saying the 1/8th great grandmother behind the sire never has any influence nor 3rd generation grandfather on X chromosome. Only influence they have is appearance through autosomal DNA. This means breeding heavy on individuals not aligned right in the ped renders there sex, reproduction, mental functions, muscle and a part of skeletal traits useless. This is cause the are passed by the X and Y chromosomes and these where they are located in this theory have no effect there. It is interesting and is heavily influenced by the fact that more is known about the female genetics and contribution on the X chromosomes. It only makes me want to know more bout the Y chromosomes and it limitations do to being small annd what it brings in function. It is called a theory and in fact has validity through science but It all still comes back to quality and culling.