Where did the Irish come from?

Many people say different things, some say from Iberia (northern Spain) as Gaels believed they were descendants of Milesians, sons of Míl Espáine.

Others believe that the Irish descend from a sunken island off the west coast of Ireland, called Tír na nÓg or goes by many names like Hy Brasil. I tend to believe the second one.

Recent DNA studies tend to support the first one, however.