I get questions quite regularly from people who are unclear on how many children Nathaniel fathered. There is some room for confusion, because some of the children were born in the ten year pause between the second and third novels, and some of them died in that period, as well.
And it is recorded incorrectly in a couple places. Here's the definitive answer in the form of a family tree. Before you click on it for a larger, more legible version, be warned that if you have not yet read the novels but intend to, you will find this chart chock full of spoilers. It also provides a little bit of context for The Gilded Hour, but nothing spoilerish at all. This chart includes all children born, even those who died at birth or shortly after.
Really I should post this in the FAQ section, but the software is misbehaving and I haven't had the time to figure out what's wrong and how to fix it.