This article begins by explaining the theory: That genes are what form our characteristics and are not affected by our environment. One the other side of the spectrum, some believe that despite our genes, our environment molds us into the people we are.
Then it delves into different arguments of psychologists, such as Niels Juel-Nielsen's study of Danish identical twins reared apart. They state that identical twins reared together in an identical environment are very similar. Therefore, If they are raised in different environments, any differences between the two can be attributed to the "Nurture" aspect. But Nielson's experiment never had a control group, so already the accuracy of this test went down.
In a separate argument, Dr. Susan Farber says the the "Nurture" aspect doesn't even exist because the individual shapes their environment. This could be valid, but there is a point made that even twins reared together differ. But for her experimentation, she chose only twins that looked similar, excluding most that can invalidate her theory.