I don't consider gambling addiction to be a disease.  It's better to call it a mental condition.  I do think those that develop addictive tendencies usually have a history of addiction in their family.  It can be drinking, drugs, t.v., or even sex.  Some people can do drugs once and not get addicted but others will be hooked on the dopamine. We all have different genetic makeup so we shouldn't judge too harshly on those with addiction problems.