I heard that if a parent was an alcoholic your much more likely to be one also..!

I heard that if a parent was an alcoholic your much more likely to be one also...why is that true?

Why is this true....i noticed that ive had alcoholic tendencies, im 21 and a female, except i dont drink everyday morning to night...eventhough u dont have to have all that to be an alcoholic (i cant just consume one drink and be satisfied , i drink to get really buzzed or drunk most of the time, i have phases where ill drink like 5 times a week and sometimes not even once a week, ive drank to the point where i dont remember a lot the next day, (blackouts but still awake), ill crave drinking..) ...anyways my dad wasn't an alcoholic where he would drink in the morning and finish bottles, & drink alone(like in the stereotypes) but hes the same way he drinks a lottt not just one drink and he used to drink often too...why is this kind of hereditary & what can we do to stop the trend (my brother is the same way he has a really good life no depression (unlike me where i suffer from depression) or anything but when he drinks he drinks to get drunk )...sorry if it didnt make sense.i wrote fast

alcoholism can be genetic.