When I ask my kids to pose for photos, it turns out one of 3 ways.
Cheesed and posed (although even cheesed and posed, she is still gorgeous):
Angry (someone has green eyes when he is annoyed/angry):
I have taken to hanging back and taking shots from behind or from the side and really, these have become some of my favorite photos. I have plenty of pictures of them smiling happily, right in to the camera. Capturing how the light hits someone's hair, or the excitement in their step, or watching them take something in when they don't even know you're there...there is just something about it.
Check it out: