So how do we know what our ancestors looked like? Well, there are several artifacts that are available to family historians and genealogists that at least describe their physical characteristics.
Below is a list of 5 different examples. I am sure that there are many more.
Passport Applications - although some applications indeed have photos (although less than high quality), a number of physical characteristics were requested by the applicant, such as stature, forehead, eye color, nose, mouth, chin, hair color, complexion, face characteristics, and distinguishing marks.
These are just 5 examples that at least give us some clues as to what our ancestors may have looked like. Maybe that red hair that you have came from your great grandfather, which was noted in his naturalization papers or voter registration from the late 1800s or early 1900s. These artifacts provide us with some distinguishing information - at least or until those unknown photos get identified, or a supportive cousin appears with the photos that we seek.
What other examples of artifacts and documents have you used to determine physical characteristics? Please specify in the comments!