Erik Plug's paper on the family origins of human capital formation has been published in the Review of Economic Studies

How important are parents for the opportunities available to their children? Unequal opportunity appeared to be genetically driven more than anything but it seems that the mothers’ education also plays a key role.

Erik explains:  Children inherit many of their parents' strengths and weaknesses, but is it due to the upbringing children  receive, or rather the genes that are passed on to them? We try to answer this question by looking at infertile couples in Denmark who get children via artificial insemination using either the eggs or sperm of donors. 

We effectively use donor families as a natural experiment where children with different genes are, as embryos, randomly assigned to either highly educated or less educated parents.  This allows us to assess  the pure effect of the environment. We can see in our study that the mother's level of education has an enormous impact on how the child performs in the national reading tests in school. In fact, these mothers seem to have as much impact as a mother who is genetically related to her child. This is, in many ways, good news for those who aren't fortunate enough to have inherited their genes from very intelligent parents and, as a result, do well in the education system.

However, we do not find the same impact of fathers. In fact, we do not find any effect of fathers who are not genetically related to their children. One possible explanation for the difference between unrelated mothers and fathers’ significance is that the donor children grow in the mother's womb already three to five days after conception and are therefore also influenced by the mother's behavior during pregnancy. For example, we can see that highly educated mothers are less likely to smoke during pregnancy, which is considered harmful to cognitive development. Another possible explanation is that mothers take most of the parental leave and therefore spend more time with the child in the first year.  We also look at adoptive families, where neither parent is genetically related to the children, and here the mothers seem to play a significantly smaller role than in donor families, and that could reflect that adoptive children were not in their mothers' wombs and often haven't been with them during the very first period after birth. 

Article citation

Petter Lundborg, Erik Plug and Astrid Würtz-Rasmussen. October 2024. "On the family origins of human capital formation: Evidence from donor children" Review of Economic Studies.