And even then, it is far from clear how much of the similarity comes from the matched genes, and how much from the original egg cells having fissioned from a common ancestor, independently of the contents of the nucleus. We know the cell itself actively seeks a goal, on its own.

As that first cell divides again and again to generate the trillions of cells in your body, mutations happen in the hundreds and thousands. Even though they started with all the same genes, they certainly don't stay that way as you grow.