I'm a beginner also, so my critique may not be too good, but your exposure is a tad bit direct. If you're shooting with an onboard flash, there's nothing you can do about it except for maybe put one of those little diffuser sock things over it. But if you look on their cheeks, you'll see white spots where the detail of the image is gone from it being overexposed. This is common when a shot is taken straight on with flash. But its not that bad, either. My shots when I try and use fill flash are A LOT harsher than this. I wish I could tone down my flash enough to limit the blown out spots as much as you have.
I agree somewhat with wishing your nephew would smile, but at least he looked at the camera

. As far as the other three shots, I think they could benefit from maybe a bit less depth of field (lower the number on the f-stop to something around f/4). BTW your subjects in the last three are beautiful, and they have gorgeous eyes (you did a good job with that). My only question is whether or not I can come to your party next year! Please!?!
BTW, I don't see any real purpose in posting how good a photo is (great, snapshot, etc.) if you don't give any tips on how to improve said shot for next time, or at least say why you like or dislike about the shot. Even when someone just asks what you think, I think we owe them a decent explanation of how to improve when we feel their photos aren't what they could be. Sorry, but I felt a need to express my opinion. You don't have to agree with me, and I respect your choice to post whatever you want.