Is that even a certainty? Let's imagine 2 simple example:

Case 1:

1 man impregnates 3 women, resulting in 3 children. In this case the next generation consist of 3 times more DNA from females than males

Case 2:

1 woman has 3 children with 3 different men. In this case the next generation consist of 3 times more DNA from males than females.

So is that enough prove that OP is not guaranteed to be right?!

They probably just thought: "it's a prototype, just needs some correction"