Is being an alcoholic a genetic thing ?

Yes, this is genetic.  They have identified a genetic marker that predisposes a person to being alcoholic.  Among other things, this means that alcohol "acts" very differently in the body of an alcoholic than a non-alcoholic.  To keep this simple, it makes physical changes at a cellular level, which is a big deal.  With that very 1st drink, the body is already starting to adapt and change with alcohol.  

Also, if it helps, what happened with your brother is very common (I'm a substance abuse counselor).  People see the ugliness of alcoholism and they swear they won't drink. or they won't let this happen to them.  But they don't understand any of that biochemical stuff I mentioned in the 1st paragraph.  

The other thing is, at 14, your older brother was trying to do the right thing and protect you, too.  But no 14 year old knows what it's like to hang with friends, be at parties, turn 21, etc.  He had no idea what it would feel like to be in that age group and be a non-drinker.  

With all this said, there's no proof yet that your brother is an alcoholic.  Most people do drink and party a lot more when they're younger.  You'll figure it out as time goes by.  Just because someone has an alcoholic parent doesn't mean they are one themselves. In fact, sometimes the genetic thing skips a generation.

It is not necessarily genetic, however, the behavior can be picked up time and time again if repeated or shown in someone's childhood.

Some scientists say it is.  Others say it is not.  My grandfather was an alcoholic; my father is an alcoholic; my sister is an alcoholic; my brother is drug addicted.  I do not drink or drug.  I think the tendency is in my DNA.

i dont think so

Many times its in the DNA. Best for you is not to drink at all, and talk to your brother about him going to AA.  Do not start drinking.

There are many theories about it. Some say it can be genetic and others say it isn’t. But whatever it is, you have seen the bad effects of alcoholism. You’ve seen the hurt and the damage that it has caused your family while growing up. Many children who grow up in families like yours promise never to end up like their parent.  And as with all things in life when you grow up,  you make your own decisions . So it is your choice to over drink and get into this habit and probably end up like your father if you let it be . Why would you want to get yourself drunk because your brother says you should ? You are your own person and you have a choice. You can decide for yourself to have one or two drinks and then stop. Drink coffee , tea, soft drinks , carbonated water and other non alcoholic drinks. Be strong about what you want your life to be like. Don’t let your brother dictate what you should do and remind him about what he promised when you were growing up. Remind him about what your dad was like and how his life turned out to be. Is that really how you want your life to be. Heredity or not, you have a choice. If you don’t make it a habit you wont become an alcoholic. https://www.jw.org/en/bible-teachings/teenagers/wh...

on some level yes .

It is more likely if you're an alcoholic, one of your parents was, too, so yes, it's often genetic.

You can have a genetic predisposition to addiction, so yes.