Instead of using complex and highly paid tools, use free pedigree chart makers like EdrawMax or EdrawMax Online that allows 100% customization as per the requirement. When completing this pedigree with autosomal recessive inheritance, individuals that are shaded are expressing the recessive phenotype and have a genotype of "RR." It should be noted here that The unusual phenotype of a recessive disorder is determined by homozygosity for a recessive allele, and the corresponding dominant allele determines the unaffected phenotype. The students pursuing a career in this stream of science should keep in mind that in the case of a rare recessive allele in the population, most of these alleles will be found in heterozygotes, not in homozygotes. The reason is a matter of probability: to conceive a recessive homozygote, both parents must have had the p allele, but to conceive a heterozygote, all necessary is one parent with the allele.