If you've been born and raised in England, Wales, Cyprus, San Marino, USA, Portugal, France, Spain, Australia, Cape Verde Islands or wherever, then you should be proud supporters of that nation.
Supporting another country is like supporting Liverpool for years and then suddenly turning to support United, and then after another few years supporting another club, and then turning again in another few years.
The only situation where you should have a choice is if you're born in one country but have been raised or have lived your life in another country. Otherwise, you should indefinitely support the country you were born and raised from. No questions asked.