I have noticed the same kinds of things in my relatives too although not quite to that extreme! Wow. I don't have an answer either. Could be many things. Some men in particular, I've noticed, seem to expect to be taken care of to an extreme extent. But there are many possible explanations, from extreme codependency, to alcoholism, to neurological problems, to mental health disorders such as perhaps Asperger's syndrome or pathological narcissism. Undiagnosed mental health disorders can lead people to self-medicate with alcohol.
Alcohol can cause brain damage, but if this has been going on since you were a kid, then there are probably other things going on here.