Countries that allow dual citizenship experience higher migration flow. They attract more migrants to their countries, and see more citizens emigrating elsewhere.
To discover this, researchers from the University of California, Irvine examined the migration patterns in 184 countries where migrants left and 24 countries where they arrived between 1981 and 2006. The paper that resulted from their work was published in the journal Comparative Political Studies in 2016.
They found that migrants are more likely to move to countries that share a common official language, share colonial roots, are closer to their home country, have higher pay, lower unemployment, and a larger foreign population. Controlling all these factors, the ability to carry multiple citizenships correlates with higher migration flow for both origin and destination countries.
When one or both countries forbid multiple citizenships, the results change considerably.
People are most likely to emigrate, when both the origin country and the destination country allow them to take more than one citizenship. They are least likely to leave their home country when both forbid it. Moving to a multiple-citizenship-forbidding country is more likely than away from one, according to the research.
For the country looking to attract talented workers, allowing dual citizenship is clearly a place to start.