In this video Enlight Photo highlights one of their products by showing how it can be used to get the best reactions possible from your kids. I personally haven't tested this product myself but the idea of using an audio trigger to get children involved in the process seems like a... sound idea. Sorry, I couldn't help myself.
“Ever wondered how to get great expressions shooting kids with your SLR? It's easy thanks to an SLR sound trigger like ioShutter. Using the ioShutter sound trigger, you can use your iPhone to set your SLR to take a photo moments after your cute little portrait subjects shout, so you're guaranteed to get them looking their best. Never get that nervous "Oh-No-My-Photo's-Being-Taken" frown again. This video will also teach you a quick and simple lighting and background setup you can use to shoot anything! Find out more about ioShutter here.”-Enlight Photo-
ioShutter Shutter Release Cable comes with an E3, N3 or Nikon DSLR connector and is controlled via their free app. If you are interested you can check out their product video below. But of course any reliable audio trigger will do.