The battle of the sexes extends all the way to our chromosomes. In some cases, the copy of a gene inherited from one parent shuts down, leaving just the copy from the other parent active and upsetting the classic rules of inheritance. Now researchers have come up with the first comprehensive map of these so-called imprinted genes in humans. Many of them lie in regions of chromosomes implicated in disease and may be involved in problems such as autism and obesity. Geneticists discovered imprinting in 1991 and now know that defects in imprinted genes lead to abnormal development and to...