One of the possible and fairly common traits of Ds is low muscle tone. This results in the "floppy-ness" of most newborns with Ds. In our case, low tone is why Jack didn't even hold his head up for such a long time, like close to 6 mos. Also that's why he rolled over later, sat up later, and walked later. Also with the walking, our Jack rolled his ankles in slightly when he did learn to stand and begin walking, so our physical therapist recommended some orthotics to help him keep his foot/ankle in proper alignment while his muscles strengthened and learned to line up without support. I have a pic of his first pair somewhere; I'll find it. Until last year, Jack wore his Suresteps whenever he wore shoes. Last year he got new shoe inserts nicknamed hot dogs. They just sit inside the bottom of his shoe and support the sole of the foot, instead of going up over his ankles too.
When Dasha came home she got Suresteps too. She had such tiny little feet when she first got home. Her pt told us they would grow when she started being able to use them more and by gosh they sure did! So Miss D grew out of her Suresteps after a few months.
Right now Jack and Dasha are both waiting for new hot dogs, hopefully they'll be in this week and then both kids can get new shoes to wear with them. Maybe I can get them matching shoes, or the girl version and the boy version of a shoe! Pics to come (posting this from a different computer than the one all the pics are on!)