Do any of these countries allow repatriation?
My grandfathers were born in Holland and Ireland.
My grandmothers were born in Croatia and Germany.
They all immigrated as kids around 1910, 1920.
Do any of these countries allow repatriation?
My grandfathers were born in Holland and Ireland.
My grandmothers were born in Croatia and Germany.
They all immigrated as kids around 1910, 1920.
If your grandfather was born in Ireland, you can likely get Irish citizenship by descent now, by registering in the Foreign Births Register. Once you get Irish citizenship, you would be able to move to Ireland.
You're asking about what is commonly known as a "Right of Return," which may allow some individuals who left a country (especially under duress) or their descendants to obtain citizenship. This Wikipedia article discusses the subject.
Of the four countries you mention, the only one listed is Germany. The article's discussion, and the other Wikipedia page mentioned therein, suggest that repatriation to Germany is available only to those who left or were forced out in the 1930s or 1940s, and their descendants.
It is not particularly likely, but depending on the circumstances, you might be a Dutch citizen. It is somewhat less unlikely that you are a former Dutch citizen. In the first case you can apply for a Dutch passport; in the second case you may have a quicker route to naturalization. There's also a possibility that you can become Dutch through the so-called "option procedure."
Whether any of this is true depends on
Be careful! If you are Dutch and under 28, you will probably lose your Dutch nationality on your 28th birthday. If your 28th birthday is in the near future, you should act with some urgency.
I'm less familiar with Croatian nationality law, but I will try to remember to check it tomorrow.