Answer:
Izzy has been diagnosed with unipolar depression. Family pedigree studies suggest that her identical twin sister, Cerole, would have about a 46 percent chance of also developing unipolar depression.
Explanation:
Twin studies with unipolar depression demonstrate a strong genetic component :
Adoption studies also have implicated a genetic factor in cases of severe unipolar depression.
Using technique from te field of molecular biology, researchers have found evidence that unipolar depression maybe tied to specific genes.