In T401564#11096686, @Samwilson wrote:

How about something like this:

{{#genealogy: person | sort_index=3 }}

With each of the lists of people then being listed by sort_index.

I'd forgotten that siblings are already listed in description order, so it just remains to do the same for children.

But yes, ordering by birth date would be better! Or perhaps by description? Which could then be set to whatever is appropriate (generally starting with the year of birth).