Taking portraits of families is a lot harder than I expected. It’s not so much the amount of light and large depth-of-field required (although that does play a part), but the fact that there are so many things going on at once. Getting everyone to co-ordinate what they’re doing becomes exponentially difficult with every extra person. And if only one person blinks, the photo is ruined.
One of the biggest assets a photographer can have is a sense of humour. If you can make your model laugh, you lower their apprehensiveness, which brings down their guard and provides you with much more natural expressions. Not to mention the fact that it’s a pleasure to see someone smiling or laughing.