Are there different forms of severity in bipolar disorder? and can it be genetic?

Yes, there are: Different forms and severity, and even cycling speed, of bipolar disorder. Some folks are more manic and some more depressed. While we are making strides w/neuroscience, we don't know the exact cause and why some folks have more pronounced symptoms than others. Peace and good health.

Yes and yes: The course of illness varies amongst individuals. This includes the severity of symptoms as well as the resulting disability. Bipolar disorder is a highly heritable (ie genetic) illness. In identical twins if one has bipolar disorder then there is a 60-80% chance the other will too. This rate is 50% for schizophrenia.