Rule #1. Don't sweat it.
This is not about mannequin perfection and fake baked happiness. This is about imprisoning those profoundly dynamic connections that only exist when you're being your true-blue, wildly authentic self.
'But howww', you say
Well, they say animals can smell fear - and guess what, so can I (and your kids). I'm a guest in your home and you want your babes to be on their best behavior, I get it! But civility and decorum are not why I'm there.
So the best thing that you can do to create a conducive environment for creating genuine photographs is to take the day off from your procreational duties, let your kids be kids, and just enjoy yourselves.
My biggest fear for our in home shoot was my crazy 2 year old. I was worried about her participating and being happy during the photography session. It's impossible for her to sit still. Because of your 'style' of photography, my kids were able to be themselves, which is exactly what I wanted. I didn't want it to be this make believe family picture that doesn't truly depict our personalities, style and interactions. Once you turned on the music and let my girls be themselves, I knew it was going to be an amazing experience and product.
Those other shoots that don't involve cherubs? Same deal.