so many surnames

[Atlas]

Why do I have so many Spanish and English surnames at Y-DNA 12 markers?

[Jim Barrett]

This is very common for anyone with a common Haplotype. You just need to upgrade.

[keigh]

At 12 markers, my brother had ancestors matches from Spain, the Atlantic coast of Europe and over to through England, to Ireland. We have an very common Irish surname. Only 2 of the hundreds of matches at 12 markers were that surname. One was a first cousin of my father and the other surname match disappeared at 37 markers. At 67 markers many of the matches that had been 0 steps at 12 are now 4 or more steps away, but we've reaching mostly Irish surnames, though not our current surname.

Probability for a 0 match at 67 markers is only 50% for the most recent common ancestor to be 2 generations away and up to 7 generations away at a 95% probability. Even with a 0 step match the chance is that the MRCA still may be hundreds of years in the past. That's the nature of Y-DNA. It is old and really slow to change.

The larger the test you do will tend to narrow down the chances that you will find a common ancestor. But where the ancestor will be historically may be a challenge. Especially if you are looking for a specific recent surname match.