I know not everyone does, but I like shooting on overcast days
Overall these are very nice
1.) I like that you don't have the group centered in the photo. However, try to stagger the people in the group next time so that you don't get heads that are lined up in a row like the two older boys' heads are. I would have had dad move his body toward his left a little (in toward the family) as he looks kind of awkward so square to the camera like that.
2.) Very cute! I don't suppose you have one like this without Mom's arm in the frame?
3.) Something seems off with his eyes. (Not the down syndrome) Maybe too much sharpening?
4.) Very cute expression on this one

I find whatever that white rounded hanging thing in the background to be a distraction though.
5.) Probably my favorite as I like the composition and his cute smile. But, his face is overly red. I don't know if you are upping the saturation levels in PS, but if you are, do it on a seperate layer and erase back his skin to a more normal looking color. That's usually what I do when I want to add some color saturation in a photo. It normally looks good everywhere but someone's skin!