For a number of reasons, one of which being that nobody here gives a fuck who dropped a load in your great-gran, why are you proud of that? Americans' obsession with 'muh heritage' is weird and incompatible with how people in Europe and Scotland view things (and often seems to go hand-in-hand with unfortunate right-wing ideas like ethnocentrism and white supremacy). It's always specific places to the exclusion of others too, and you're an example of that - why are you proud of and more interested in the Scottish part over the others? You guys are always wanking yourselves off about 'links' to Scotland and Ireland, but hardly anyone does the same thing about 'links' to England or France or wherever, even though there's loads of Americans descended from people from those places too. It comes off as selective interest in places you entertain fantasies or misconceptions about (Scotland and Ireland are often romanticised), and self-aggrandising because the perceived link makes you feel cool or special or badass or whatever.