So my wife's far extended family just showed up from Sweden and one of them had a curious tattoo that turned out to be the "family mark". Such a thing I kind of knew existed but it never connected that it was a reality (if that makes sense). In the past 5 days my googlefu has completely failed me on any information about these things. What are they called? My family is from Denmark, did they do these things? Is there any kind of record of them anywhere?