Dimples are a physical trait that is determined by a person's genotype. The genotype for dimples is either Dd or DD, where D is the dominant allele and d is the recessive allele. If a person has two dominant alleles (DD), they will have dimples. If they have one dominant and one recessive allele (Dd), they will also have dimples. If they have two recessive alleles (dd), they will not have dimples.