Hi Barbara

Let me explain the sentence as I intended for the sentence to come out and
the rest will fall into place.

Every one of us had 8 great-grandparents. Those would be considered
branches on our family trees. We can trace ONLY relatives who are related
to you on your mothers mothers side, back to a few thousand years. Same
is trues, back a few thousand years on your dad's dads side, but ONLY those
two specific branches back in time.

To trace back in time to relatives connected to another of your remaining
6 G grandparents (in the example above) progenitors, you should need to
use cousins of yours

Please see the page: http://www.familytreedna.com/tc.html I think that
the page will help too.

Best regards

Bennett Greenspan FTDNA HOUSTON