I get this question frequently, though just as often asked if I am Irish; which I am (by birth, ancestry, and citizenship). I was born in Co. Donegal and my family moved to Canada when I was four. However, my paternal grandmother is a Graham from Scotland so I am of 1/4 quarter Scottish descent. Incidentally, the Graham of Montrose tartan is my all-time favourite of the tartans I am "entitled" to wear!
My wife wears tartan kilted skirts I have made her though these are typically Welsh tartans as she is half-Welsh and half-Mik'Maq (Native Canadian). People sometimes ask her if she's Scottish as well.

Is mise le meas,

Seán Liosliath Ó hAirt