How to become an Iranian Citizen?
A woman who marries an Iranian citizen automatically becomes an Iranian citizen, though she may also keep her previous citizenship. Otherwise, to become a naturalized citizen of Iran, you have to live in Iran for 5 years and be at least 18 years old, and not have a serious criminal record or be a military deserter. The child of an Iranian citizen is also automatically an Iranian citizen, no matter where born, so this allows for descendants of Iranians in other countries to claim Iranian citizenship, even after generations, but I don’t know whether Iran would ever be aggressive in claiming these citizens.