Answer :
Heterozygosity of genes sometimes allows natural selection to maintain deleterious alleles. Sickle cell anemia is only exhibited by people who carry both alleles as recessive.
The recessive/recessive allele can become advantageous in a different environment or time. Sickle cell recessive allele protects their carrier against acquiring malaria.
The recessive/recessive allele can become advantageous in a different environment or time. Sickle cell recessive allele protects their carrier against acquiring malaria.