Age of parents and cognitive ability of their children – is there a negative, no or positive correlation?

In recent decades, the average age of parents at the birth of their children has increased. Older parents have generally completed their education, are emotionally more mature and usually have work experience and their own income, which can be an advantage for their children’s development. On the other hand, the risk of mutations (in the father) increases as the parents get older, and there are also general health risks (especially in the mother). This means that both positive and negative factors for cognitive development are linked to the age of the par-ents. In our study with five diverse samples from different ethnic backgrounds, we covered an age range of 6 to 18 years (primary and secondary schools in Austria and Ecuador, N=920), used tests for both fluid and crystallized intelligence, and used target-specific measures for control variables. We calculated correlations and regressions between parental age and chil-dren’s intelligence (controlling for parental education, parental income, number of children, birth order and sex of children). Positive (linear) correlations were found in four out of five samples, on average r=+.10 to r=+.11 (N=920). Curvilinear (quadratic, inverted U-shaped) correlations are higher than linear ones (R=.20). The association with the age of the mother is somewhat stronger (father RF=.16 vs. mother RM=.19). The effect of parental age remained positive when other family variables were taken into account in a regression: beta=+.19. The par-ents’ level of education was more relevant (beta=+.28). Even if the possible effects are not large, there are predominantly positive (statistical) effects of the age of parents at the birth of their children on the development of their children. The slight inverted U-shaped curvilinearity in-dicates an optimal age for expectant parents of around 25/30 to 40 years.