How come all down syndrome children have the same facial features?

Chromosome influence: The size & shape of the skull & facial features of Down syndrome patients is heavily influenced bu the effect of the extra chromosome present in every cell of the body.The same goes for eyes, hands & feet all of which require a lot of decoding during formation to produce the structures. Many other chromosome defects produce some common features to those born with the abnormality.

Chromosomes abnormal: Down syndrome is a disorder of trisomy (3) number 21 chromosomes. As a result the facial abnormality is shared by everyone with the same extra chromosome.