If you have an Irish or UK passport, you can enter Ireland without a visa. You can reside in the State without restrictions and can access State-funded services, including healthcare. Not everyone who holds an Irish or UK passport actually considers themselves to be ‘from’ Ireland or the UK. Indeed, you might have spent your whole life in the USA, Canada or Australia. But if you have a valid passport from one of these countries, then you have the right to live in Ireland for as long as you see fit, irrespective of your age.