Researchers get viable mice by editing DNA from two sperm
For many species, producing an embryo is a bit of a contest between males and females. Males want as many offspring as possible, and want the females to devote as many resources as possible to each of them. Females are better at keeping their options open and distributing resources in a way to maximize the number of offspring they can produce over the course of their lives. In mammals, this plays out through the chemical modification of DNA, a process called imprinting. Males imprint their DNA