Instructions: Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
Input: Fraternal, non-identical are two other terms for dizygotic twins, which make good study subjects because they share many environmental conditions, but only about half of their polymorphisms.
Output:
What are two other terms for dizygotic twins, which make good study subjects because they share many environmental conditions, but only about half of their polymorphisms?