France:
My kids are in their 30s and the law has changed since they were born:
Actually, I had always intended to keep my own name, but when you live in France it's automatic! You don't lose it when you get married; Many women choose to be known as Mme Hisname, but on legal documents even on identity cards it says Mme Hername, épouse Hisname:
And because of this, there's no "keeping his name when you get divorced": he actually has to give his permission for that to happen, otherwise it's automatically back to your own name:
And none of this Hisname for boys and Hername for girls: all the children born of the same two parents have to have exactly the same surname, so the choice you make when the first is born dictates what the rest of their siblings will be called:
These days you can choose to give your kids Hisname, Hername or double barrel them (without hyphens, in either order):
What you cannot do is pick an entirely new name and say "we are going to be the family Lavende: M, Mme and three kids all called Lavende:":
The name you get from your parents is the one you will have to use your whole life (unless you do a very complicated and costly court procedure: it happened to someone I knew whose husband was not the father of her kid: after the divorce she had another whole lot of legal procedings to undertake to change the kid's name to that of the new husband -who was also the genetic father):
Unmarried parents
If the parents agree whose name the child will have and make a joint declaration then the possibilities are the same as for a married couple, but if the mother registers the birth and the father only does the paperwork afterwards, then the child will have the mother's name:
If the parents are not married there is a procedure (this is France - they are world champions of paperwork) whereby the father can recognise his offspring by making a declaration even before the birth.......... and if I understand things correctly
www.demarches.interieur.gouv.fr/particuliers/choix-nom-famille-enfant-pere-mere
if the parents don't agree and are concerned that the other may try to give their name to the child by making an anticipatory declaration, one or both can lodge an official objection and then the "registrar" will give the child both parents' names in alphabetical order