Mark and Mathew are identical twins who developed from a single zygote and share identical DNA. Nevertheless, as they develop, differences in physical and psychological characteristics become evident. These differences are due to:
A) each twin's unique genetic blueprint.
B) the pruning of unused neurons in each child's brain.
C) allele variation.
D) epigenetic change.

Question

Quizplus · Accepted Answer

Epigenetic changes, which alter gene expression without changing the DNA sequence, may occur differently in each twin due to different environmental experiences and therefore contribute to differences in physical and psychological characteristics. A and C are incorrect as both twins have identical DNA and genetic blueprints, and allele variation would not differ between them. B is incorrect as neuron pruning occurs in response to environmental experiences but does not cause differences between identical twins.

Mark and Mathew Are Identical Twins Who Developed from a Single