I proposed the jus sanguinis because it's extremely common, even in Europe. You aim for a double jus sanguinis, which means that both the parents have to be citizens in order to pass down citizenship to the children.

Usually you have some other ways to acquire citizenship which involves marry someone, being in the country for a vast amount amount of time without leaving, having a job, stuff like that. Which means that is hard but not impossible to acquire the citizenship. That allows to keep immigration low and to proactively absorb immigrants in the main stock.