Which of the following statements is TRUE?

a. DZ twins are no more genetically alike than any pair of siblings.
b. MZ twins develop from the separate fertilization of two ova.
c. DZ twins develop from a single fertilized ovum that divides into two identical cells.
d. Members of any set of DZ twins are more similar to each other in terms of their
psychological traits than are MZ twins.
e. MZ twins generally are more available for research than DZ twins.

Answer: a. DZ twins are no more genetically alike than any pair of siblings.