[Campbell Biology P.421] The text states that epigenetic variations might help explain cases... | Practice Question

The text states that epigenetic variations might help explain cases where one identical twin acquires a genetically based disease, such as schizophrenia, but the other does not, despite their identical genomes. Which of the following best explains this phenomenon?

  • A: Identical twins inherently have slightly different DNA sequences from birth.
  • B: Environmental factors can cause permanent mutations in one twin's genome, leading to the disease.
  • C: Differences in environmental exposures can lead to varying DNA methylation patterns and gene expression, even with identical genomes.
  • D: Only the twin who acquires the disease inherited a faulty gene from their parents.

Explanation

The text explains that despite identical genomes, epigenetic variations—alterations in DNA methylation patterns—can lead to different gene expression and phenotypes, which might explain why one identical twin develops a disease while the other does not, particularly when environmental factors play a role.