Answer:
heredity
Step-by-step explanation:
According to various researchers, the aspect of identical twins is more significantly described in terms of the relation of heredity and environment. It is more generously described by keeping identical twins in the first place because they share similar genes or genetic compound.
The research has shown that identical shares most of the genetic material as compared to the fraternal twins. Psychologists and researchers have described that identical twins are also being identified based on the intelligence levels by keeping them in different environments. However, the intelligence of an individual is based 60% on the genetic composition whereas 40% on the environmental factors as per the various research that has been conducted.