On compromise... sometimes The Almighty sorts things out

Grand Dukes Adolphe and William IV were Protestants. In the contract of William's marriage to the Catholic Marie Anne of Portugal, it was agreed that any sons would be brought up as Protestants and any daughters as Roman Catholics. The marriage produced no sons. Consequently, the religion of the House of Nassau changed to Roman Catholic when daughters of William succeeded to the throne.

Grand Ducal Family of Luxembourg
My wife is like 99.5% Luxembourgish.