nitpick: probably you mean "be sure to have a citizenship in a EU country or Iceland, Liechtenstein and Norway", which has nothing to do with the place somebody is born.
In this regard, Ireland has some exceedingly generous right of return laws. If you have documented lineage from an Irish grandparent, the process of obtaining citizenship is completely painless.
I obtained citizenship by this route in 2004 and was able to live and work in the UK with no visa requirement.
I obtained citizenship by this route in 2004 and was able to live and work in the UK with no visa requirement.