It's a basic human desire to seek recognition by others, and physical resemblance is often that first form of recognition we experience.
You can see a new parent flush with pleasure when that physical resemblance is commented upon: "He looks just like you," or "She has her mother's eyes." Having to wait until he was 45 years old, Eric Mueller began Family Resemblances to document and celebrate family members with shared physical characteristics and as a way to understanding this experience.
An experience nearly impossible to describe. The feeling of seeing someone who looked looks like you: a mixture of relief, wonder, and joy, but also sadness for all the lost years of shared memories with biological family members.