By choosing Kamala Harris as his potential vice-president, Joe Biden hasn’t just picked a running mate, but a high-profile political heiress. A good choice for running mate Younger, but not too much Kamala Harris will be 56 on 2020 Inauguration Day, much younger than then-78-years-old Joe Biden. Bold, liberal, pragmatic She is elected and known at a national level, and has both executive and…