What is normal to one does not have to be normal to someone else. If you work at an Instutition for the Criminally Insane, the common thing is for the person there to be an insane criminal. They do outnumber the staff members. For most of the people there to be criminally insane establishes the commonality and normalcy as deviant behavior to the staff members who are not insane or criminals.
On the other hand, the individual insane criminal can see the staff members as being deviant and different from him- or herself. In the way that the Institution is a society, the situation is the same in the larger society, which is our nation.
What is common and normal for the larger proportion of society establishes both the commonality and the normalcy for that society. That is why the left has been so busy changing society to its own image of what is normal and common. They have used different means to achieve their ends, but they have been very successful. And you can see just how successful they have been by comparing how our society is now based on what it was not so many years ago.
This change can not be solely attributed to a rule of evolution of a society based on advances. The changes have been both technological and moral. It is the moral change in which we now find out ourselves up the proverbial creek.