Out of all the types of shoots I have done I enjoy family and kids shoots the most. These shoots are extremely easy to shoot. They also give a different feel to the photos. Every family is different and it shows in the images in my opinion. The kids in my experience usually bring the most personality to these photos.
I think that it is a lot easier for kids to be expressive in images. They are way more carefree and just are themselves. Kids don't care about posing a certain way and are not concerned about how the look to the outside world. They do not care about showing emotion. It allows the photographer to get the most unique photos. I always want the photos I take to reveal a little bit about who the subject is.
Most times during these shoots people don't even realize I have been taking photos because they are interacting normally. If it is a kids shoot try to capture them in their element. If they want to play then let them. If they want to speak about things such as cartoons indulge them. For family shoots I encourage the family to just do things how they normally would. Eventually they become less focused on the camera and just conduct themselves as they would normally.
In conclusion I think we can learn from the carefree attitude of kids. There is no harm in letting loose and just being you. In fact I'm sure most photographers would prefer it. That moment of authenticity might create some amazing images.