I grew up in a family that drinks.  My real father was a drinker - I'm pretty certain he was an alcoholic, he was certainly a physically abusive drunk & drug user.  I have not seen him since I was 7.  My 2nd 'father' (1st step-father) was a verbally abusive drunk.  I would regularly see them drink a bottle of wine a night each & get through 1 bottle of gin a week... my brother likes his drink, but stays with beer and has a gut to show for it, he drives for a living so rarely gets plastered.  my half-sister recently (10 months ago) got so drunk on one holiday of hers that she collapsed hitting her head badly, losing consciousness and ending up with a subdermal haematoma that has left her with continuing problems included repeated periods of her collapsing/paralysis down one side of her body - she does now thankfully seem to be recovering.  There are rumours that I have a half-brother but to be honest, I rarely see him.  He has issues - what the cause is (drugs/alcohol) is anyones guess. he has little communication with the family despite living with my sister.  My 2nd step-father does not drink, is not verbally abusive, is not physically abusive and is a really nice man.  Unfortuantely my mother still drinks like 2 fish (wine & spirits) and gets through more than enough for both of them.
My father-in-law also drinks - mostly beer, but you never seem him have more than 2-3 beers, you will never see him drunk but the evidence however is in the recycling. My mother-in-law drinks in moderation, my husband's brothers: 2 drink, 1 does not (he decided he was allergic to hangovers many years ago and stopped completely which probably saved his life, he is now type 1 diabetic dependant of insulin)
I don't drink much at all - close to none whatsoever (half a beer once or twice a month, a hot toddy if I can't sleep when I have a cold.  If I consume 6 units a year, it would be a bad year... I joke that I gave it up when I started to learn to drive, it was not really a joke.  I was the taxi service for my mother & ex-step father, in return for unlimited use of the car whilst I was at home. 
 
My OH has naturally gone my way, never being that fussed about it, but we still worry about 2 out of 4 of our parents.