This thread has been interesting to read as it unfolded. I can't say I don't understand why someone would get upset over a person wearing a clan tartan to which they have no affiliation - I definitely understand where that objection would come from. If I may, I'd like to give some insight.

I have always found difficulty in relating to people on a personal level; it would probably be safe to say I'm a bit eccentric and simply different. I have three dads and two moms. My last name is French, but I have no French ancestry. It took me a long time to understand the concepts of tradition and peer pressure because they seemed strange to me; you couldn't convince me to do something 'because that's what you're supposed to do', nor 'just because everyone else is doing it'. I had to have a reason that made logical sense to do it. This 'different' kind of existence caused me some hardship as I grew up and tried to understand the world around me, because this wasn't the world most people lived in. At a young age, I moved to another state with some family. I attended a school completely new to me with people I couldn't immediately relate to. The way I talked was different and the things I liked were different. I quickly became the victim of extensive bullying simply because I was different and I was passive. I wasn't born into that culture and they treated me like I wasn't good enough for them. Being young as I was, I took these things to heart and thought there was something wrong with me. Eventually though, I had a life-changing revelation for the better. The bullying and harassment wasn't a pleasant experience by any means, but was one I later came to appreciate for the knowledge and understanding I ended up with.

How does this play into this thread? The knowledge and understanding I ended up with was that a person's words or opinions only have as much meaning to you as you personally give them. Further, you're the only one who can give a person control over your emotions/feelings. A person cannot forcibly make you offended or make you upset. It's something that you choose to do. You can take what a person says or does to heart and give it meaning, or simply not.

In that same context, you should not limit yourself to a certain set of rules (regarding tradition) if you do not personally find it important. You should live your life as you see fit, regardless of what other people think, because it is your life and not theirs. No matter what you do in life, somebody somewhere will/would take offense. I personally wear any tartan that appeals to me, be it because of the pattern, colors, history, or what have you, because I like what I like and nobody can change that. If someone decides to take offense, that's their choice. We're all humans floating on the same rock in space; why bother getting upset over petty differences in personal opinions? It's certainly not going to fix anything.

So, to the op, you must ask yourself, 'How important is it to me personally that a clan tartan be worn only by someone affiliated with that clan?', and 'Should it only be worn by someone affiliated with that clan?'. You're the only person who can answer those questions.

Cheers,
-Jake