SRRD_2017_34.pdf (1.65 MB)
Cognitive ability and fertility amongst Swedish men. Evidence from 18 cohorts of military conscription
preprint
posted on 2017-12-11, 15:25 authored by Martin KolkMartin Kolk, Kieron BarclayKieron BarclayAbstract: We examine the relationship between cognitive
ability and childbearing patterns in contemporary Sweden using
administrative
register data. The topic has a long history in the social sciences and
has been
the topic of a large number of studies, many arguing for a negative
gradient
between intelligence and fertility. We link fertility histories to
military
conscription tests with intelligences scores for all Swedish born men
born 1951
to 1967. We find an overall positive relationship between intelligence
scores
and fertility and that is consistent across our cohorts. The
relationship is
most pronounced for transition to a first child, and that men with the
lowest
categories of IQ-scores have the fewest children. Using fixed effects
models we additionally control for all factors that are shared across
siblings, and after
such adjustments we find a stronger positive relationship between IQ and
fertility. Furthermore, we find a positive gradient within groups of
different
lengths of education. Compositional differences of this kind are
therefore not
responsible for the positive gradient we observe - instead the
relationship is
even stronger after controlling for both educational careers and
parental
background factors. In our models where we compare brothers to one
another we
find that relative to men with IQ 100, the group with the lowest IQ
scores have
0.58 fewer children, and men with the highest IQ scores have 0.14 more
children.