When a single trait has identical alleles it is said to be homozygous. An allele constitutes a specific gene, inherited from parents during reproduction. Alleles may be dominant (represented by two capital letters, RR) or recessive (represented by two small letters, rr).
rr would be an example of a homozygous recessive allele as a homozygous allele would have the same allele twice and a recessive allele is the lower cased allele of the pair.
