In 1980, Sweden became the first European monarchy to declare equal (full cognatic) primogeniture, meaning that the eldest child of the monarch, whether female or male, ascends to the throne [REF].
Sometimes religion is affected; for example the British monarch, as head of the Church of England, is required to be in communion with the Church, although all other former rules forbidding marriage to non-Protestants were abolished when equal primogeniture was adopted in 2013.