Anglo-Irish-Scottish DNA

Hi

I have DNA from the British Isles and I can see through other relatives who have taken the test that it comes from my paternal grandmother's family. Her father was a Cavazos and her mother was a Gracia, they lived in (close to) Monterrey.

Anyone else out there unexpectedly have British/Irish/Scottish genes? . My percentage is very small (2%) so timewise it must go way back, but its also there in my siblings (1-2%) and another relative two generations above me (Ireland/Scotland 6% and England/Wales/Northwestern Europe 5%) so I dont think its a mistake. My best guess is the slave market of Sevilla, where white slaves (often fishermen taken captive in the North Sea isles) were sold along with slaves from Africa. But maybe someone researching Cavazos or Gracia has come across an Anglo name?

Regards
Denise