According to official stats, 16% of Irish residents are citizens of other countries. Keep in mind that this number will exclude foreign nationals that got Irish citizenship through naturalization (and therefore became Irish citizens).
https://en.wikipedia.org/wiki/Foreign-born_population_of_the...
Most recent numbers from the UK list 16% of the population being "foreign-born". While this number may be similar to Ireland, it still counts someone as foreign born even if they became UK citizens by naturalization.
Also, consider that one of the most prominent migration sources for the UK is of Irish nationals (that can live and work in the UK even after brexit). Irish culture is not too dissimilar to UK culture (especially considering that Northern Ireland is currently part of the UK).
If anything, Ireland experienced more foreign culture immigration than the UK, not less.
Your point is invalid.
As far as I know, those born in Northern Ireland have automatic right to Irish citizenship for being born in the island of Ireland.
https://www.citizensinformation.ie/en/moving-country/irish-c...
> The Good Friday Agreement, which was signed between the Irish and British governments in 1998, confirmed that people born in Northern Ireland could choose to be either British or Irish citizens.
> Since 1 January 2005, if you are born in Northern Ireland, you can claim Irish citizenship if your parent (or parents) are either British or Irish citizens, or one of them has lived on the island of Ireland for at least 3 out of the 4 years immediately before your birth.
