I apologize if this hypothesis sounds strange by I was wondering if any research had been done on a phenomenon which I've seen and have corroborated with many other - the idea that over time spouses tend to start looking similar to each other.
My hypothesis is that this is really a one-way street with the wife tending to look more like the husband. The reason being that after coitus her body is flooded with his genetic material which may lead to some mixing of DNA outside of the egg. Furthermore once the woman is pregnant she enter into a symbiotic relationship with an organism whose DNA is approximately 50% foreign. Her body must then adapt to the presence of that new genetic material.
I realize this may sound strange and Lamarkian but I was curious if the phenomenon itself had been investigated.