Originally Posted by
osarusan
As John 83 said, you will have to register their births. My daugher was born in Japan but is automatically an Irish citizen due to me being born in Ireland. If she has children in the future, she'll have to register them for citizenship (if they're born outside Ireland of course). Interestingly, as long as they are registered before they themselves have children, they can also register those children as Irish citizens. It could theoretically go on generation after generation.