What does "my clan" or "my chief" mean?

[Scotus]

I am very aware, however, that absence makes the heart grow fonder, that distance can obliterate memories of hardship and suffering and give the individual a pair of rose-tinted spectacles about many things others might prefer to forget.

What you say is true. I think this is why many Americans and Canadians participate in Highland games, eating haggis, etc., as you say. To be fair, there are Scotsmen, born and raised, who also love to participate in these things, and see it as an important part of their culture.

As long as they don't take the next step down the road and start believing "that tartan is mine and no-one else must wear it" or worse still "my clan right or wrong". That way is the way of division and strife.

I agree. As I state, for me it's more of a point of reference, sense of belonging to something that is related to my ancestry, etc. I believe history and the past are very important.