Skip to main content
Biology LibreTexts

5.S: Pedigrees and Populations (Summary)

  • Pedigree analysis can be used to determine the mode of inheritance of specific traits such as diseases. Loci can be X- or Y-linked or autosomal in location and alleles either dominant or recessive with respect to wild type.
  • If the mode of inheritance is known, a pedigree can be used to calculate the probability of inheritance of a particular genotype by an individual.
  • The frequencies of all alleles and genotypes remain unchanged through successive generations of a population in Hardy-Weinberg equilibrium.
  • Populations in true Hardy-Weinberg equilibrium have random mating, and no genetic drift, no migration, no mutation, and no selection with respect to the gene of interest.
  • The Hardy-Weinberg formula can be used to estimate allele and genotype frequencies given only limited information about a population.

Key Terms

Pedigree charts

mode of inheritance

genetic counseling

incomplete penetrance

variable expressivity




autosomal dominant

autosomal recessive

X-linked dominant

X-linked recessive

Y-linked inheritance


mitochondrial inheritance (mtDNA)


product rule

sum rule





Hardy-Weinberg formula

p2 + 2pq + q2=1

Hardy-Weinberg equilibrium

assortative mating

random mating


genetic drift