Let's say two people are born in a hospital at the same time. Now person A spends his entire life sitting around his house and not moving much. Person B spends most of his life traveling around in high speed cars/planes/and even takes a few trips to space. Considering time slows down the faster you go, does this mean that Person B would be younger than person A by an extremely small amount of time? I'm not sure if you want to take in the effects of gravity on time but I'm sure that makes a difference as well. What I am trying to say is, is everyone on a different time so to speak?