Are codominance and multiple allele inheritance the same thing?
No they are not the same thing. Multiple allele inheritance is when there are three or more distinct alleles for a single gene. Inheritance in heterozygous phenotypes is more complex than Mendel had with his peas. Blood type has three main alleles so there are more combinations for heterozygous phenotypes. Codominance is when both alleles penetrate to the phenotype to produce a checkered appearance. Basically this means the is a mosaic of two unblended phenotypes. Heterozygous blood types are codominant in that both proteins are on the cell surface. However a multiple allele inheritance could easily produce an incomplete dominance so the heterozygous phenotypes formed a series of intermediates between the homozygous phenotypes. There is a gene MC1R that converts red phomelanin to brown melanin. There are more than 7 alleles for MC1R. Only one allele converts all the melanin so inheriting this allele in two copies the hair is brown, The is an allele than converts no phomelanin and this
