"As identical twins share exactly the same genes and non-identical twins half the same genes as each other, twin studies are extremely useful in separating these genetic and environmental components.
(identical twins; share; ) (exactly the same genes and non-identical twins; half; the same genes; T:As identical twins share) (each other, twin studies; are; extremely useful in separating these genetic and environmental components) (each other, twin studies; in separating; these genetic and environmental components)
identical twins exactly the same genes and non-identical twins each other, twin studies each other, twin studies
share half are in separating
the same genes T:As identical twins share
extremely useful in separating these genetic and environmental components
these genetic and environmental components