It's an early lesson in genetics: we get half our DNA from Mom, half from Dad.
But that straightforward explanation does not account for a process that sometimes occurs when cells divide. Called gene conversion, the copy of a gene from Mom can replace the one from Dad, or vice versa, making the two copies identical.
In a new study, researchers investigated this process in the context of the evolution of human populations. They found that a bias toward certain types of DNA sequences during gene conversion may be an important factor in why certain heritable diseases persist in populations around the world.