Quick Question: Do Sims need a Surname?

I’m making yet another new Sim and his backstory is that he’s a former street kid
fighting to make himself respectable (and rich wouldn’t hurt either).

He’s of at least partial Selvadoradan descent . I want to call him Nicolas (aka Nicky or Nicco). If I can get away with it I want him to just have this first name. His family is unknown.