Gervayse Pyncheon is the grandson of Colonel Pyncheon, whom Gervayse discovered dead at the housewarming party for the House of the Seven Gables. After this traumatizing event, Gervayse Pyncheon takes a dislike to the House of the Seven Gables. He spends much of his time traveling in Europe. His wife is European and his daughter has been raised abroad.
(By the way, Mr. Holgrave writes down this part of the family history and publishes it as a magazine story. Mr. Holgrave reads the tale to Phoebe in Chapter 13.)
Despite Gervayse's physical separation from the old homestead, he's still a chip off the Pyncheon block. He's greedy enough that he's willing to trade anything – even the House of the Seven Gables – to Matthew Maule II in exchange for that fabled deed to the lost Pyncheon properties in Maine. He's also willing to give Matthew Maule II hypnotic control over his daughter, Alice Pyncheon, which doesn't turn out well for anybody. For more on the fallout of this particular episode, check out our thoughts on the character of Alice Pyncheon.