An on-line dictionary defines clan as:

clan (kln)
n.
1. A traditional social unit in the Scottish Highlands, consisting of a number of families claiming a common ancestor and following the same hereditary chieftain.
2. A division of a tribe tracing descent from a common ancestor.
3. A large group of relatives, friends, or associates.

We obviously fall under the third definition, so the motto is appropriate. Regardless of our blood relationship to a Scottish clan we are all members of XMTS by choice, so I don't see the motto as excluding those who have a blood claim to another clan.

Brian