Most of us, at one time or another, imagine what it would be like if there were another person just like us. Twins already know what this is like. They have the same family, the same childhood experiences, and in the case of identical twins, the same DNA, yet they are separate people who eventually build their individual lives. But some twins share more than others. Read about twins who share things the rest of us cannot understand in this article I wrote for mental_floss.