I have to agree here with the above postings. Since familial tartans were not even in place until the 1700s it could be argued that your family wore whatever they could get at earlier dates. That being the case, there is no claim to a tartan that is not somehow owned (and yes there are a few) and their use controlled.

Burberry is an example of a tartan pattern that has strict controls on it manufacture. (They are of course a commercial enterprise not a family anyway.)You might be able to wear their kilt, but you will likely never find a supplier who will reproduce the tartan without permission from the company.