They do not often use family name though many have one.
Children have the same family name as one or both of their parents.
My phone number is not even in the family name.
As a child he had made much of his family name.
I'm sure you know him by his family name at least.
In the early 1980s she started using the family name.
Since they are many, the word could have become their family name in course of time.
But she kept the family name of her first husband.
If he had a family name it was never used.
But he never allowed her to use his family name.