Harms

Many parents believe that kids “will drink anyway” and they have little control over their alcohol use or access to it. Some parents feel pressure to allow kids to go to adult-supervised drinking parties with friends. The truth is, adults have more influence than they think—whether they are coaches, dance teachers, big brothers, or mom and dad. Kids say parental disapproval is a key reason they choose not to drink, according to surveys by the National Center on Addiction and Substance Abuse at Columbia University.

Enabling kids to drink hurts their health, can program them for addiction and other mental disorders, and it’s against the law. It’s time to draw the line.

According to the AMA, the brain’s frontal lobe and neuro-pathway connections continue to develop through age 20. Damage from alcohol at this time can be long-term and irreversible.
It’s a class 1 misdemeanor for parents and adults to knowingly host parties for anyone whom they “know or should know” is under age 21. You may be liable in civil litigation if those minors are injured in an alcohol-related accident. Source