They say if you go back far enough everybody will find they are related to royalty in some way or another. They spread it about a lot in those days (and no doubt still do) but I wouldn't put too much reliance on a connection just because the surname is similar. I have been doing a bit of genealogy and found that what seems to be the case almost never is and you can only ever rely on hard documentary evidence. Everything else is just simply unreliable and there is little, if any, documentary evidence relating to the general population before the 19th century other than some church records. As to tartans, in Lady Jane Grey's time tartan-wearing was about as likely to be met in London as men from the moon and probably even less thought about.