Answer: I would talk with them and tell them that alcohol in moderation is completely fine. So long as they are the legal drinking age. And that their first time to drink it I'd like for them to do it with me so we can tell what negative effects it will have on them. That and we'd know their tolerance for it.
Answer:
If you're descending the trail, step aside and give space to the people climbing up.
Genes. Genes are what you get from your parents, proteins are what you get from eating meat, codons are basically the stuff in genetic codes and base pairs make up your DNA. :)