The third arcanum names the error committed towards children — one's own and those who were in one's charge. Children abandoned, handed over, unacknowledged; those used as a means in the affairs of adults; those whose future was traded away for someone's convenience.
A descendant meets this as difficulty with children in the broad sense: children do not come, or come with difficulty, relations with them do not take shape, and a wall stands between the generations that nobody built on purpose. Sometimes the storyline unfolds differently — a person spends a whole life looking after other people's children and cannot have their own.
The working-off is simple to state and hard to carry out: to invest in the children who are already there. One's own, adopted, pupils, the younger ones in the family — the difference here matters less than it seems. What matters is finishing: not abandoning halfway the person you have taken on.