What is is my mum has Bipolar Disorder & i was wondering if it is hereditary?

The disorder is 75 to 80 percent hereditary, according to Dr. Candida Fink, a child and adolescent psychiatrist and author of Bipolar Disorder for Dummies and The Ups and Downs of Raising a Bipolar Child. Stress, family life, emotional and psychological stresses should also be taken into account.