It is a myth and like most myths, if told over and over again it almost becomes fact. There are NO rules or regulations on who can wear a tartan.
Below is the Official View from a member of the Lyon Court of Scotland, the body which regulates clan crests and coats of arms.
Alastair Campbell of Airds, Unicorn Pursuivant of Arms
Below is the Official View from a member of the Lyon Court of Scotland, the body which regulates clan crests and coats of arms.
Alastair Campbell of Airds, Unicorn Pursuivant of Arms
"Often over the years one has heard people explaining how they have 'the right' or that they are "entitled" to wear this or that tartan. In fact no such right, in any legal sense, exists for them or for anyone else. The only considerations which govern the wearing of a particular sett are usage and good taste.