Related Experiment Video
Updated: May 27, 2026

Stable Isotope In-Vivo Labeling for Mass-Spectrometry Identification of Paternal Metabolites Transferred from Sperm to Oocyte During Fertilization
Published on: June 17, 2025
Abstract:
Abstract It is often assumed that family size and income would be positively related if unwanted births among the less advantaged were prevented. But this assumption rests on a prior expectation that family-size preferences bear a direct relation to income in modern societies. Data on such reproductive preferences in relation to economic status from 13 studies in the United States dating between 1936 and 1966 do not support the notion of a positive association between reproductive preferences and income. Only when Catholics are considered is there even a U-shaped relation between family-size desires and income. These results cast doubt on the notion that the economic theory of demand for consumer durables is relevant to reproductive motivation. Rather, the data lend credence to the idea that significant non-economic influences associated with prosperity depress family-size desires among the well-to-do. Only if these influences are specifically weakened by a counter-force (such as Catholicism) do wealthier people show a preference for somewhat larger families. In no case, however, are the Catholic/non-Catholic differences in reproductive preference large. Moreover, no economic group, even among non-Catholics, prefers very small families.
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