Bipolar is proven to be genetic, but is often highly influenced by society. Even though you may inherit the bipolar gene, not everyone with the gene will necessarily become bipolar. A person's tolerance for stress has a lot to do with whether or not they develop it. If a person lives in a low stressful environment their chances of developing Bipolar are a lot less than someone that lives in a highly stressful environment. Since Bipolar is inherited, if there are a lot of members in your family diagnosed with Bipolar you are at a high risk of receiving the gene, but since it is heavily influenced by environment, only one out of every four people with the gene will become truly Bipolar.
Borderline Personality Disorder.
Borderline Personality Disorders are believed to be genetic with a strong environmental influence. Almost everybody that's diagnosed with this disorder are thought to come from one of three families, which are an over involved family, a neglectful family, or an abusive family. Many people feel the stress levels that come from these particular families are the key triggers for Borderline Personality. Although many scientist are unsure BPD is genetic since there has been no genetic test done to prove it, they strongly believe it's much like Bipolar.
Many scientists think that BPD is a mixture of biology, psychology, and social triggers. They believe this because the people that they feel display signs of BPD are shown to have temperamental mood abnormalities such as being emotionally unstable or impulsive, which are two traits that are often known to be hereditary and only occur when the brain has a lack of the chemical Serotonin.
The way a child is raised can determine a huge part in contributing to BPD. If the parents are emotionally unstable, impulsive, or abusive (verbally, physically, or sexually). The chances are much higher for the person to develop BPD. Only in very few rare cases were the parents completely normal.
