A Diasporan was a term given to Humans who came from a planet which one of the first waves of colonists from Earth had settled in the early 22nd century. They tended to be tough people which was inherited by their children in both looks and constitution.
Some of the earliest generations of Diasporans were known to suffer from mutations as their ships were not properly shielded from radiation. This resulted in certain child being bald by loss of hair at an early age or retaining their hair which would remain completely silver in color.
Harb Tanzer was of Diasporan stock. (TOS novel: Spock's World)