Scion:
a young member of a rich and famous family [Cambridge Dictionary]
Noted in “Ethics Committee Acknowledges Investigation of John Duncan Jr.”, RollCall:
The House Ethics Committee acknowledged Tuesday an investigation of Rep. John Duncan Jr, a scion of a Tennessee political dynasty who announced his retirement in July.
Duncan, a Republican, came under fire that month after reports that his campaign paid his son, John Duncan III, almost $300,000. In the five years since the younger Duncan pleaded guilty to a felony charge of official misconduct. Those payments were made in monthly installments of $6,000 recorded as salary expenses, according to the Knoxville News Sentinel.
Possibly not young enough to qualify for use of the term if he has a grown child? In fact, the “scion” has been in office since 1965, according to RollCall. He’s more of a patriarch.
