What is unusual about the piano player when Vincent and Irene attend a concert?

The piano player's distinct characteristic that stands out during the concert is that he has 12 fingers. This abnormality is significant within the narrative of GATTACA, as the film explores themes of genetic engineering and the potential enhancements that come from it. Having 12 fingers could imply his genetic manipulation or enhancements that allow him to play the piano with extraordinary skill, showcasing the extremes to which humanity can go in seeking perceived superiority through biotechnology. This character serves to highlight the world of GATTACA, wherein individuals are often judged based on their genetic make-up, and exceptional physical attributes can lead to extraordinary talents, contrasting with Vincent’s genetically "inferior" status.