The first time Eric Mueller saw his mother, he cried.
It was 2009, and he had just tracked down his only living birth family member, a cousin. The cousin gave Mueller a box of photos of his birth mother, who had died.
Mueller has always been fascinated by people who looked like their family members. He resembled his adopted siblings in mannerisms and food choices, and he and his adoptive father shared an interest in photography and a propensity for chunky black glasses.
But he didn't look like anyone else he knew, and it bothered him.
"When you see people who look alike, you feel a pang of loss, because they have something you don't," said Mueller, 52, of Minneapolis. "It's something I always wanted to have."
On seeing the photo of his biological mother, he finally found it: "I looked so much like her," he said.
Now, Mueller highlights the features other people share with their own kin.
A professional photographer, he last summer launched a self-funded project, called Family Resemblance, that groups together relatives and explores their similarities in a single frame.