Set, believe me, irish history is not my forte. I believe there were many mixed marriages between the irish and the moors, sailors who decided to stay awhile and so on, but I don't believe it was religion my sources were referring to when the spoke of the moors.
Most of my 'irish' stories have been, rather...poetically told.
A couple of years ago I listened to a brilliant radio documentary on CBC on Ireland and music, history ect. Paddy Malone, lead man in the Chieftains, he believes the irish/celtics origins can be traced to northern india. He insists you can trace a fairly direct route the celts followed to reach present day gaelic/gallic stongholds.
One of the most compelling of his ideas was that the celtic route can be traced back to india, through musical instruments and the similarities in style, rhythm and sound.
I imagine during this long journey they mixed it up with a lot of different folk. The irish have only really one similar trait, really thin skin. As for colouring, it pretty much runs the gamut. Perhaps it just a story to romantise one particular group.
But then again, I grew up with folklore, music and newspapers from home.
I would love to know the truth as well.