How exactly does gender work? It's not just about our chromosomes, says biologist Karissa Sanbonmatsu. In a visionary talk, she shares new discoveries from epigenetics, the emerging study of how DNA activity can permanently change based...

It's easy to assume a cat's coat pattern is based exclusively on genetics, but that isn't entirely the case for Siamese cats. Their unique coloration comes from a combination of genetics, a fragile enzyme, and losing heat from little...

Paul Andersen explains how X inactivation works in mammals. This process was first described by Mary Lyon. Each cell in a female will have on activated and one inactivated X chromosome. This explains why almost all calico cats are...

X-chromosome inactivation in various sex chromosome genotypes (XX, XY, XXY, XXX, XO) and resulting Barr bodies; the Lyon hypothesis; the proposed mechanism of Calico cats