This whole book seems to be written in a very pointedly casual, offhand style, almost exaggeratedly breezy and entertaining. In German I want to say something like locker-flockig; not sure if that's quite right, but it's close. I appreciate the effort to make it readable and entertaining, as opposed to dry or academic, but for my taste this is pretty astonishingly far in the other direction.
In more standard style, when the thing possessed (here: pedigree) is an abstraction, not a literal object, it's really better to use 'of,' not the apostrophe possessive. So in better English, it should really read '... pedigree: that of Johann Wolfgang von Goethe.' Could you just say something like
eine überraschend schicke/vornehme Herkunft: die von Goethe.
'Tony' isn't serious either, it's closer to 'posh' than to 'elegant.' It and 'horsed around' both seem very, well, anbiedernd, like the writer is exchanging a sly wink with the reader. To get that tone across, the German needs to be equally slangy and unserious, even pointedly cute and joky.