I don't know about that. RealityCheck had two X chromosomes, herself . . . one from her dad . . . and one from her mom. So her son's X chromosome could have as much from his grandma (her mom,) as from his grandpa (her father.) But, then, he got his Y chromosome from his dad. His dad contributed 50% of his DNA. Her dad contributed only half of the DNA in her. She only contributed part of that to son. Father's DNA would outweigh Grandfather's DNA. Least, that's how I figure it. (?)