We study the relationship between personality traits and fertility using a survey of Norwegian men and women born from 1927 to 1968 (N = 7017 individuals). We found that personality relates to men's and women's fertility differently; conscientiousness decreases female fertility, openness decreases male fertility and extraversion raises the fertility of both sexes. Neuroticism depresses fertility for men, but only for those born after 1956. The lower male fertility in younger cohorts high in neuroticism cannot be explained by partnership status, income or education. The proportion of childless men (at age 40 years) has increased rapidly for Norwegian male cohorts from 1940 to 1970 (from about 15 to 25 per cent). For women, it has only increased marginally (from 10 to 13 per cent). Our findings suggest that this could be partly explained by the increasing importance of personality characteristics for men's probability of becoming fathers. Men that have certain personality traits may increasingly be avoiding the long‐term commitment of having children, or their female partners are shunning entering this type of commitment with them. Childbearing in contemporary richer countries may be less likely to be influenced by economic necessities and more by individual partner characteristics, such as personality. Copyright © 2013 John Wiley & Sons, Ltd.