This story is part of a week-long series on reproduction, from prenatal testing to childfree Reddit. Bacteria do it. Viruses do it. Worms, mammals, even bees do it. Every living thing on earth ...

This story is part of a week-long series on reproduction, from prenatal testing to childfree Reddit. Reproduction is messy. The genetic swaps and recombinations that occur when gametes merge don't ...