A decade and a half later, scientists at the University of Alberta looked for fetal microchimerism in the brains of fifty-nine women following their deaths. Each of these women had given birth to a son. The scientists detected male DNA in 63 percent of the women’s brains and in multiple regions throughout them. The oldest subject was ninety-four years old, meaning her son’s cells had lived in her body for most of her life.3 Our children are, quite literally, frequent and widespread residents of our brains.
