No person shall sell, give or otherwise supply alcoholic liquor, wine or beer to any person knowing or having reasonable cause to believe the person to be under legal age, and no person or persons under legal age shall individually or jointly have alcoholic liquor, wine or beer in his, her or their possession or control, except in the case of liquor, wine or beer given or dispensed to a person under legal age within a private home or with the knowledge and consent of the parent or guardian for beverage or medicinal purposes or administered by either a physician or dentist for medicinal purposes and except to the extent that a person under legal age may handle alcoholic beverages, wine and beer during the regular course of his or her employment as provided by state law.