[@Altered Tundra] I understand it's your right, but it's also the right of the player to have the necessary information, so they can create the best character that they can within the parameters given by the gm. It's your responsibility to make sure everyone's on the same page. 
And it's not assumed the characters have to famous, since I see more rps that don't specify a famous person for a face claim. It's either a drawing or realistic picture. If they what a certain age range for the picture that's stated, but no one ever says famous person. Sheets tend to get rejected based on character info.