I have recently been getting to know someone for marriage and I have discovered the mans father is an alcoholic. The man I want to marry does NOT drink however his father does and this is also done inside his house. Does this affect my decision in marrying him ? Or affect anything in the future of our marriage ?

Marriage is a very sacred institiition and you need to discuss these fears openly with the man you are thinking of marrying. It is a lifetime decision to make so you need to be 100% sure about the man's social habits and also if his dads influence will impact him negatively. Please try and do some more research before plunging into this matter