Multiple alleles are a set of three or more genes, controlling the same character located on the homologous chromosomes.
A set of multiple alleles may contain three, four or more members. All the members occupy the same locus in the homologous chromosomes since all these alleles are formed by the mutation of one gene. Out of several allelic forms of a gene, a given diploid individual possess any two alleles of the allelic series and its gamete carries only one allele.