New evidence for dysgenic fertility for intelligence in the United States

Data were taken from the 1994 National Opinion Research Center survey of a representative sample of American adults to examine the relation between the intelligence of adults aged 40+ and their numbers of children and their numbers of siblings. The correlations were found to be significantly negative at -0.05 and -0.09, respectively, indicating the presence of dysgenic fertility. Further analysis showed that dysgenic fertility is present only in females. The correlation for females between intelligence and ideal numbers of children was effectively zero, indicating that if women had the numbers of children they consider ideal, dysgenic fertility would be reduced.