When you grew up and started a family of your own, you took the name of the home you settled in. In a lot of cases, your name didn’t change at all, not if you kept living with your parents and grandparents and so on. If you settled in the home of your partner, you took your partner’s family name. If you both decided to live in a separate home entirely, apart from both of your families, you’d both get the name of whoever’d taken care of that home before you.
