We already know that children from larger families generally have lower educational attainment and IQ scores, worse employment outcomes, and are more likely to engage in risky behavior.
Has the direction of causation been determined? Do children from large rich families do worse than children from small rich families? (Also: the paper linked on the words "educational attainment" in the original article seems to contradict this quotation in its abstract: "First, neither birth order nor childhood family size significantly influences the level or growth rate of wages..."[0])
[0] http://ideas.repec.org/a/ucp/jlabec/v9y1991i4p413-26.html