Here is a more fun question: What is the optimal reproductive strategy that also maximizes the chance that the children also reproduce? I will add as an established fact that daughters has a higher base chance of reproductive success than sons, but sons have higher base variance.

Game theory should always be asked when biology is involved. I am not sure myself on the answer, but it seems more plausible than the article's "teenage girls are annoying" theory or the speculated "son preference" theory. If there is an optimal strategy, such a strategy may result in a small biological effect which makes parents look for a new chance of reproduction once the majority of child investment is done, resulting in the statistical data that shows 20.12% becoming 20.48%.