The theory is that they can be, yes, but the strongest factor is how one is raised and what one believes. So, your dad, had problems, and feelings he did not know how to deal with after his divorce. Instead of finding the right help for him to deal with his feelings and thoughts, he started drinking to cover over the feelings. He may or may not have had underlying alcohol addiction genes , we don't know.
His drinking escalated, destroyed his liver, which is the largest organ in the body , besides the skin, and it is the organ that clears out all toxins and alcohol is very hard on the liver. It destroys it. so, once the liver stops functioning properly, it cannot filter out the toxins , junk, and all of them go to the brain, and cause more damage. this damage can cause alcoholic induced hallucinations.
It can also break the spirit down due to unhealth, so that spiritual intrusions can occur.
So, you see, that it is mostly due to what he did and did not do, and that is the way it is for most so called mental illnesses, regardless if one could develope something.
If you have some personal concerns about your own feelings and how to deal with them in a healthy way then find a good way that works for you, I think this is the best method , because it is the only one that acutally clears them so they are resolved and don't return, eftmasters.com , you have some good therapists that know it in your country. emotional-health.co.uk eftuk.net and others.