The shopkeeper is a Pyncheon ancestor from about a century before who "found himself involved in serious financial difficulties" (1.36). He tried to get himself out of these difficulties by converting part of the House of the Seven Gables into a shop. But once he died, the rest of the family immediately locked the shop door and refused to speak of it again: they all felt profoundly ashamed that a Pyncheon should be soiling his hands with trade. Hawthorne gets pretty sarcastic while describing this long-lost Pyncheon, since it's obvious that trying to open a store is more honorable and useful than "urging his hereditary claim" (1.36) to those stupid long-lost lands in Maine. Nonetheless, the Pyncheons are such snobs that they are ashamed of this guy.