Virtually nothing is known about the man who calls himself the Clown other than he claims to be the brother of original Clown, Elliot Franklin. Although at times has even claimed to be Eliot Franklin himself. Due to the nature of the character, it's possible he isn't in anyway related to the original Clown at all.
Clown was created by Dark Reign: Zodiac writer Joe Casey and artist Nathan Fox. Joe Casey, who had previously used the original Clown heavily in his Deathlok series, admits he only created the character because he couldn't use the original Clown since he had become a gamma monster called Griffin.