This is by I gave DS my surname. It was very important to me that DS shares my name and identity as I am his mother.
I know most women don't mind giving up their family name but I've never been comfortable with the idea that a woman should change her name to the man's name and that all children should have their dad's surname. To me it's old-fashioned inequality that carries on this idea that the male is the head of the household and thus his family name is more important. It isn't, so I don't subscribe to it.
I am so happy DS has my name, he has his dads name as a middle name too.