In my opinion and in my experience - Current "sept" clans are an invention by some to modern organizers and authors to include anyone with even a remotely sounding Scottish name or family tie.

The only real way to discover which clan your family might have ties to would be to track and trace back the family line. In my particular case, if I go by last names alone, my clan ties are grossly wrong. Remember that in the purest form, Mac means "Son-of". So if your Dad's name is Donald, you then become a MacDonald. If his name was Neil you become a MacNeil. This sometimes also works with job titles or professions - if your Dad was a barrel maker you could be a MacCooper.

This can have little if anything to do with your actual clan. In my case, my male line is more closely tied to the Gunns and the MacGregors (depending on the time frame.)

Try to track your family back! That is the only sure way to establish a clan tie.

And while you are doing this, keep careful record of all the surnames that you find. It’s always nice to have more tartans to choose from, if you are a purest and want to have some ties to the tartan that you choose to wear.