Simplify the following text for a Grade 5 native English-speaking person.
Original: The reasons behind Chico 's and Harpo 's stage names are undisputed , and Gummo 's is fairly well established . Groucho 's and Zeppo 's are far less clear .
Simplified: The brothers were Chico , Harpo , Groucho , Gummo and Zeppo .