Why are two children born to the same parents (not identical twins) unlikely to have the same genetic makeup?
A) Crossing-over recombines portions of sister chromatids.
B) Fertilization provides a new pairing of chromosomes.
C) Each sperm or egg has a random assortment of chromosomes, half from each pair.
D) Chromosomes align themselves independently during meiosis I.
E) All of the answer choices lead to genetic differences among siblings.

Question

Quizplus · Accepted Answer

All the listed mechanisms contribute to genetic variation among siblings who are not identical twins. Crossing-over (A) mixes genetic material between chromosomes during meiosis, fertilization (B) combines genetic material from two parents in unique ways, the random assortment of chromosomes (C) in gametes ensures a mix of genetic material from grandparents, and independent assortment during meiosis I (D) further shuffles the genetic deck. Each of these processes ensures that, barring identical twins, siblings will have a unique genetic makeup.

Why Are Two Children Born to the Same Parents (Not