Thanks for replying.

To answer your questions:
The differences at these two markers are not the only differences, but the only ones at makers that haven't been flagged as "rapidly mutating". They are also the 2 markers where I vary from the 12 marker modal (and yes, the modal values are 14/11), but with so few samples I'm not sure how valid modal values are.

Only a few of the participants have uploaded GEDCOMs and none go back very far. Mine is one of the oldest and it only goes back to the early 1800s (4 generations). And of those, none share a common ancestor.

The project is clustered by DF21+, DF21 untested, and the I haplogroup. I don't think there are enough particpants yet to start other clusters.

My closest "matches" within the surname project are:

GD 1 @ 12 markers (3 matches)
GD 5 @ 25 markers (1 match)
GD 7 @ 37 markers (1 match)

My main question is - are these distances and the fact I'm the only one with the 15/10 combination enough to make me consider whether there was a non-paternity event? Or should I just be patient and wait for more lads to join the project?