Answer: a. Identical twins who grew up together are essential for these studies so that we can see if environment is really an influence or not. Maybe it could be a different case for each one of them. So by comparing them we can know.
b. The results of inherited variation would be that the offsprings would get the same type of characteristics from their parents while environmental variation is variation causedby the environment like heat, temperature, etc.
Step-by-step explanation: