1- Asking why someone does not have children.
In my point of view I consider this behavior is very rude because it is a personal subject. Also, maybe the person who not have children have a medical problems. But, in some culture the persons who not have children like to discuss with others.
2- Bringing your dog into a restaurant.
In my opinion this behavior is rude because when I decide to go to the restaurant I want to feel relax with my family because my children and I scared of doges. Also, I see this behavior not show on etiquette inside the restaurant. However, in other culture this behavior is not rude and normal things from their lifestyle.
3- Kissing in public.
In my opinion this behavior is rude because it oppose our Islamic law and our societies and traditions. But, in other culture this behavior is very normal and like to doing in front of people to show their love.