That's just relative, no? Surely people with children pack more, but the concept is the same - you pack a lot the first time you travel with them, and then narrow it down the more you travel with them.
(Said as a parent)
There's a bell curve. Infancy is the left, age 4+ is the right. The swell is toddler age.
For me, it was having children that really forced me to learn to travel light. We lived in Chicago and going to the airport meant walking to the transit stop to get to the airport, so I needed a way to carry luggage (I did so on my back) for a mile while also being able to push a stroller.
Same exact principles apply. You just add the children's stuff, taking care to pack those light too.