Atheist; May I respectfully say, that though you have such certainty that there is no God, you do not really know what is going on in your own (or your wife's, if you are male) body.
Ref, DNA; Women do not only pass on DNA, but can receive it too from their children. During pregnancy, foetal cells get into the mother's bloodstream mixing freely with her own cells and resulting in what scientists call a 'microchimera', a single organism harbouring a small number of cells from another individual.
Microchimerism is the reason doctors can use the mother's blood to do genetic testing looking for markers of disease in the DNA of the growing foetus. Though the number of foetal cells in her bloodstream will drop after the birth, some can stay for decades, even for the rest of her life. These cells can become an integral part of her body, and may have both positive and negative effects on her health - a sort of backwards inheritance.
Source, extracted from; [i] She has her Mother's Laugh; the powers, perversions and potential of heredity by Carl Zimmer. [i] Picador, 656pp. £25.