I don't know, I think if your family runs to alcoholism it's best to teach your children to just avoid. Teenage drinking is being shown more and more to be
especially dangerous, and add a genetic predisposition to "My mom let me drink wine with dinner starting at age 10" and I think you're just giving your child a head start.
As for kids dining out, I think it is entirely appropriate once your child has mastered proper manners- that age probably varies from child to child.