[Campbell Biology P.334] Why do consanguineous matings matings between close relatives incre... | Practice Question

Why do consanguineous matings matings between close relatives increase the probability of offspring having recessive genetic disorders?

  • A: They increase the mutation rate for recessive alleles.
  • B: Close relatives are more likely to carry the same harmful recessive alleles.
  • C: They cause dominant alleles to become recessive.
  • D: They guarantee that offspring will be homozygous for all traits.

Explanation

The text states, 'people with recent common ancestors are more likely to carry the same recessive alleles than are unrelated people.' Therefore, if two close relatives mate, there is a higher chance that they both carry the same rare harmful allele, and their child could inherit that allele from both of them, resulting in a homozygous recessive disorder.