In Spain, everyone has two surnames. Your first surname is your father's first surname, and your second surname is your mother's first surname. What this means

In Spain, everyone has two surnames. Your first surname is your father's first surname, and your second surname is your mother's first surname. What this means is that in a family of mum, dad and kids, only the kids will share the same surname. We had a German friend who married a Spanish man, and she insisted on changing her surname to his when they got married since that was traditional for her. But for Spanish people this was really weird, since it sounded like they were siblings. I actually haven't asked them since they had kids, but I guess their kids must have his first surname doubled (which is not unusual - María Sanchez Sanchez just means that the first surname of both parents was Sanchez).