By wearing a Tartan, you are not claiming to BE anything. You can wear it in honor and respect of those it represents.

If I wear the Moffat Tartan, I am honoring my great-grandfather, I may be able to "claim" kinship, but in reality I am honoring that line.

If you choose not to wear it, for the reason that you might offend, that is your choice, but as we have said here with any tartan, if you wear it, wear it proud, and know who it represents.

You could wear it in memory of those whom you knew/know in the USMC.

I did not serve in the military, but I have respect for those that have served, and those currently serving.

I will get a Leatherneck kilt to honor the institution of the Marine Corps, and to remind myself who they fight for.