There is no real evidence at all but it makes a romantic story esp for Americans. But how many Spanish lads would had to procreated to changed the population to that degree? In 400 years but nobody knowing? Crazy. In fact DNA has basically put the lid on this one. Also as well just across the sea in Wales, you get a very similar look too (Catherine Zeta, John Rhys Davis etc) but no sentimental tales of hapless sailors. When the last ice age ended, people migrated north from the enclave in the Pyrenees. They got to Wales and Ireland (you can literally see over on a clear day) and stayed. Others followed. Coastal Atlantic people are more closely related to each other than we anticipated.

Not say that there are not very interesting heritage mysteries. There has been hitherto unknown Native America dna found in Icelandic people and nobody knows why 1% of Scots have Berber ancestry. Or why or how some Lowland Scots called Colquhoun/Calhoun including Ulster Planters have Sephardic Jewish heritage (probably Spanish Jewish who came over in the 17th century and "passed"). Funny old world, it is.