Do traits that occur in people with Down Syndrome sometimes occur in their siblings?

If similar traits occur in siblings, it would likely be a coincidence unrelated to Down Syndrome. The genetic basis for DS is well-known: a triple copy of chromosome 21. This is rarely a result of the parents’ own genetic makeup, but results from a defective sperm or egg cell. While there is a rare “partial trisomy” of Chromosome 21 which results in a fewer number of the classic traits, generally you either have full DS or you don’t. And the odds of a family having more than one child with DS are 1 in 100.

However, both of my kids, neither of whom has DS, have inward bending pinkies, and one has separated big toes. But theirs are inherited characteristics unrelated to chromosome 21.

I didn’t know my pinkies had a name.
Mine aren’t so pronounced but wow.

@asmonet Just for the record, the picture isn’t of my kids, but my daughter’s pinkies are every bit as bent as those, Jayne’s a bit less. It’s a dominant allele F trait they inherited from Mrs. Harp. Are your mom’s pinkies bent too?

I’ve never noticed anyone with bent pinkies. I guess I never pay attention to peoples hands.

You have the nerdiest awesome family. I don’t think I’ve looked. I’ll have to confiscate her hands momentarily when she gets home. :)