Moors and Arabs left surprisingly little DNA in most of the Iberian peninsula, except to some extent in the far South. Likewise the Germanic tribes that preceded them.

In this sense, the Spanish are generally more similar to the Irish, Welsh, Scots, Cornish, and Bretons than to the Germanic peoples of Europe.

And then there are the Basques of northern Spain, who apparently pre-date even the Celts (who in turn pre-dated the Germanic peoples and Romans).