Interesting. A friend of mine in Tulsa had a grandchild born with this condition, which is treated with surgery immediately upon delivery. The mother was quite young - 19, iirc - as was the father. The mother was white and the father Hispanic. We gave them some furniture when we moved.
I remember this happening to our teacher way back when I was in third grade - she was white, not too young or old. Her husband was a farmer.
I heard a doctor whose son has Downs Syndrome say that our genetic code is so complex that it’s a miracle anyone is born without defects.