I have answered this completely, you are just wanting your hand held.
Legalized pot no more undermines parental moral authority than legalized alcohol. In fact, I think legalizing the substance may give parents a bit more moral authority in discussing the use of intoxicating substances.
If anything, illegal anything makes a substance more tempting and more difficult to control.
Does making consumption of alcohol by people less than 21 years old make people less likely to drink?
I disagree. When it comes to something like drugs becominmg legal the parents moral authority goes out the window, the state has deemed it acceptable. Parents cannot stop their 18 yr olds from buying alcohol in most states. In a teens mind all they can think "well it's legal what do they know".
If you plan on a legal career or anything requiring a clearance then a pot bust is going to ruin it before you even start. Yes that is a consideration and yes teens do think like that. I did.