I am a pureblood, but until recently that was unknown. A great great grandfather in the 1500's cast a spell on the family lineage that magically hid the muggle/born pureblood status except from the head of the household or some other designee. Turns out Wolf's family is related to all the founders. Wolf has more of an inquisitive nature, and until certain recent events with Crouch Jr, viewed death eaters and the whole pure blood thing with curiosity. Wolf in known to be the mad scientist, always working on some new spell or the like. Sometimes, even putting his life in danger.
Wolf isn't a pure Englishman; his grandmother is a witch from Mexico who migrated to Britain years ago.
Wolf used to suffer from Amnesia and has gotten his memory back. Since then his mind has been flayed by Leglimens torture by Crouch Jr and currently has Sorting Hat memories inside my head due to an interrupted experiment. Is he even sane? Some may not think so.
Wolf is also inventing Avian Tongue; it's like parseltongue, but for the birds. He also has a nondescript looking book that he puts his magical research into. It's currenty functioning like a type of penseive, but with limited intelligence. But Dumbledore has that at the moment.
Wolf's family has recently decided to end the spell that has been hiding their family ancestry from detection. Here is a sampling of newspaper articles created, though do remember who is the author of the articles.
Wolf's family recently revealed their magical heritage, that they are pure bloods, but it is complicated. The Ancestor who cast the spell in the 1500's, each of his grandparents was directly related to one of the founders of Hogwarts. While some may question this, do recall that wizarding wars do cause such information to be lost occasionally. Also, that most ancient families did not track descendants of squibs or weak wizards, even when the children or grandchildren and their descendants are fully magical. So even given faulty recording methods, Wolf's family is pure blooded.