The subject of which tartan was proper was important in the days when clan loyalty was at issue. Fortunately, we no longer have wars between the clans and this is a whole lot less of an issue.

People can wear a tartan for loyalty to their clan or because they like that tartan. And, there are variations in clan tartans (Modern, ancient, weathered, etc.). The more I look at it, the more I think Ancient Forbes is pretty grotty, but I needn't wear it!

Just steer clear of the folks who believe that you need to be born into a family to wear that Tartan.