Generally, clan-ness is passed from father to son. In your case, I assume your father was a Sharkey, and so was his father, and so forth, so that would be the "usual" way to trace clan affiliation. However, in the US of A, there is no really strict requirement that you trace your line patrilineally. You can join any clan you wish, and if you want to wear the tartans of any of the names in your genealogy, go right ahead. My maternal grandmother was my link to a Scottish name, so I wear the tartan of that clan.
Helpful?