User blog comment:LittleFlowerKusa/Clone Aging/@comment-5188108-20120909174017/@comment-432124-20120909211258

Well, I'm thinking that it's because the way that Cadmus manipulated Superboy's DNA made him like that because it was half-Kryptonian, half-human and the process was really tricky. The other clones are OK because their DNA was easier to manipulate, as they were fully human and much more familiar to human science.