I like alcohol. I like the taste of good beer, wine, or whiskey. I like being buzzed or tipsy, and I especially like hanging out with friends who are in the same state of mind. However, I have never been black-out drunk, nor have I ever done anything I seriously regretted the next morning (there have been "That was dumb." moments, but no "Oh dear god what have I done?" moments). Ultimately, Drunk Me has never done anything sober me wouldn't do under the right circumstances.
As for my personality when drunk, my friends say I barely change and am just a little more outgoing. Basically, I slowly transition from being passively friendly to actively friendly. Most people don't actually change their personalities while drunk, they simply become more intense versions of their sober self.
That doesn't mean that your parent is a bad person, but that anger IS an aspect of their personality and it IS being magnified when they drink. Also, why do they drink? How often? Do they drink with friends or alone?
Being drunk doesn't change your behaviour or bring out your "true self", it just amplifies what you already are feeling. If you're sad and you drink, you'll be depressed. If you're frustrated and you drink, you'll get angry. If you're happy and you drink, you'll have a good time. If someone becomes unpleasantly passive aggressive when they drink, then they were already holding that aggression internally. Very rarely have I been mean to someone when I drank, but every single time it was motivated by feelings I had when I was sober but was too polite to act upon.
That's also a good tip to remember: drinking when you're sad or angry will only make things worse. Don't drink to cope.
Oh, and the "I was drunk" excuse isn't valid. If alcohol effects you so much that you cannot control your actions, then you definitely shouldn't be drinking.
