I wanted to ask, I wish to marry a marry who is looking into converting. He is a previous Christian but not practicing, the same as his family however in the past he used to drink alcohol and his parents still do. Would his or my previous consumption of alcohol have an effect on future children. Is this marriage still permissible even though his parents still consume alcohol

If he is really accepting Islam and going to live his life accepting to Islam then his past will not play any role in his future life and future generation.