You live where ? <| sep |> Well the real reason people with down syndrome look the same to us is actually social conditioning . There are a few distinctive characteristics that they have in common and overall they look different from what we are used to seeing , so our brain groups them together . It ' s the same reason white people tend to think all back people or Asians look similar , and vice versa for other races . Your brain just isn ' t trained to find the subtle differences like it is within your own race . That may sound controversial , but that ' s the real answer to your question it ' s more psychological for you than it is physiological for them . If , for example , you worked with down syndrome kids the you ' d get a better appreciation that it ' s a misconception . But if you wanna know the underlying genetics that causes the distinctive features I can try to answer that too . Edit Downvote if you want , but it ' s the real answer . Here ' s 4 sources on this psychological shortcoming literally called the otherrace effect 1 . The OtherRace Effect and Facial Identification 2 . The OtherRace Effect Develops During Infancy 3 . Own and otherrace face identity recognition in children the effects of pose and feature composition 4 . The role of skin colour in face recognition