They actually tested this, a famous photographer Francois Bernell, searched the world to find "twins". These twins were people unrelated, but looked identical. They followed up the art project with a research experiment to look into their DNA and found that they actually did share more genetic material than the average person.

"Dr. Esteller found that the 16 pairs who were “true” look-alikes shared significantly more of their genes than the other 16 pairs that the software deemed less similar. “These people really look alike because they share important parts of the genome, or the DNA sequence,”

https://www.nytimes.com/2022/08/23/science/doppelgangers-twins-dna.html