As a dual citizen who hangs out with polyglots carrying several passports each, I can attest that identity is a complicated thing. It’ll never be captured adequately by lists of checkboxes — from age and sex to race, religion, profession or indeed citizenship. Just glance across Europe right now.
In one corner, Ukrainians are fighting heroically to preserve their distinct national identity against Russia, whose despot denies they have one. Some of the defenders speak Ukrainian as a mother tongue, others Russian or something else. The older ones used to be citizens of another entity, the Soviet Union. But now their allegiance is to Ukraine.