Will we soon return from Space Travel to find we are younger than our children

Dr. Albert Einstein proposed the theory that clocks run faster the further away from the ground they are

If we assume that Scott (is an astronaut) and Mark his twin  were born at exactly the same time, and if we rule out all other factors (including gravity, which also slows time) that means that Scott is younger than his twin, having spent more time in a fast-moving space station in which time slows down.

How much younger? By our calculations, those 486 additional days that Scott spent moving at about 17,0000 miles per hour slowed his aging by about two one hundredths of a second compared to his twin

So wherefore Earth bound time?
It is utilitarian.