Matches from paternal grandmother?

[NCroots]

My son matches several men at 37-markers with a distance of 3 & 4. They all have the surname Clark (our surname is Canipe). Looking at our family tree, I found that my 4th great-grandmother's (father's mother's mother's side) maiden name was Clark. Could this be the connection? For some reason I was thinking y testing: father's father's father's line exclusively, without the female lineages.

Also, my father's grandmother was a Grigg; Her ancestors came from Cornwall. My son has two exact matches at 12-markers with Grigg men who come from the same village as my Grigg ancestors. The best I can tell, our 8th great-grandfather's were brothers. That is remarkable. But again-- and I'm sorry if this is a really stupid question-- do the y-tests show genetic relation to the female lines of the paternal side?

[ltd-jean-pull]

The tests won't show anything to do with female ancestry or sisters of your father or paternal grandfather etc, but it's rather a coincidence that someone matches from one of your known lines.

Sometimes when you match several men with the same surname it can be because one person tested. Maybe they were surprised with their matches (not the surname expected for example, such as Bloggs) and then perhaps a brother tests and they confirm they really do have the same father, and then a cousin agrees to test and he matches, and then a patrilineal second cousin tests and he doesn't match (but still doesn't match the surname the family goes by - he matches Grants...a NPE somewhere), so his first cousin tests ....and so on. You can start to think "90% of the matches are Bloggs", but it's just that several gt-grandsons of one Joe Bloggs tested and what they don't know yet is that Joe Blogg's father was actually Mr Riley, the next door neighbour.

[NCroots]

Ah, got it. I was confused about the female lineages on the paternal line. We are thinking there might be a NPE for our line because we are not matching other Canipes here, or on 23andMe, or on GEDmatch. A lot of investigating needs to be done. Thanks for your help!