A remarkable new study published in the European Journal of Personality looks at effects of personality on how likely a person is to have children. So if you are an extravert, look out. You may be the most fertile
Using survey and birth registry data for men and women born between 1927 to 1968 in Norway, researchers from the International Institute for Applied Systems Analysis (IIASA) combined personality surveys to examine the connections between fertility and personality for both men and women. They used questionnaire data from over 7,000 individuals.
Lead author Vegard Skirbekk notes that it is normally difficult to know exactly how many children men have because information is often not matched in the registries, “but for Norway we have very exact information.”
Results showed that personality related to fertility in different ways for men and women. For example:
- Conscientiousness decreased female fertility
- Openness decreased male fertility, and
- Extraversion raised fertility for both men and women.
Additionally, the researchers noticed a decline in producing children among neurotic (moody or emotional) men, but only for those born after 1957.
The authors note that changes in fertility for this group of men could be explained by couples today typically waiting longer to have children, though they say it cannot be explained by partnership status, income or education.
Population changes are an important set of data for IIASA, which researches projected future changes in sustainability, climate, energy and food security.
In Norway, the proportion of men without children by age 40 increased between 1940 and 1970, from 15% to 25%. For women, it increased only slightly, from 10% to 13%.
Skirbekk notes that though the study focuses on Norway, the results have wider implications:
“Many trends that have been observed first in Norway – increasing cohabitation, divorce rates, and later marriage, for example – have then been observed later in many other parts of the world.”
He also notes that “it remains to be seen if this phenomenon will also spread.”
This study is the first of its kind to study the decline of fertility rates in Europe as they relate to personality. The authors say their findings show that “childbearing in contemporary richer countries may be less likely to be influenced by economic necessities and more by individual partner characteristics, such as personality.”
A 2012 study showed that personality traits may determine how long a person lives.