Why do the British have more than one middle names?

Question

For ex. Prince William's name is William Arthur Philip Louis or J.K. Rowling's baby girl is named Mackenzie Jean Rowling Murray

Answer 1

she has two last names not two middl enames\

its just culture
Inm some coutnries there are none, in US its typically one
and royalty alwyas have a lot of name no matter where they are from

Answer 2

Is that like why all Americans have names like Billy-Jo-Jim-Bob, or Mary-Sue-Gracie-Lou?
Not everyone in the UK even has a middle name. I have a christian name, and a surname. That's it.
Your question is so an American generalisation of the English way. I believe you may think we all speak similar to Dick Van-Dyke in 'Mary Poppins, drink nothing but tea, & have wonky teeth..
:)

Answer 3

The British aren't the only people that sometimes have middle names. My fiance is British and he has two middle names because his parents couldn't decide on one.