Clones are organisms that are exact genetic copies. Just after birth, they do not show any variation. The only way they can show variation their lives is by mutation and if this mutation results in the expression of characters that makes Though, genetic variation in their next generation can occur by other means too.
Genetic variation can be caused by a mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism’s offspring).