My foster sister is in prison. Her four children see her briefly once a month, as part of a 368-mile round-trip that takes up their entire Saturday. (Before she was transferred last month, the trip measured 404 miles). She has missed so many milestones and special events in her children's lives: first days of kindergarten, Christmases, birthdays, Halloweens, first school dances. More than three percent of American children have a parent behind bars; so many that even Sesame Street thought to address the issue in a heartbreaking video and a recent initiative. With Mother's Day upon us, I have to wonder: As kids grow up, what's it like when the person they love most is locked away?