A recent study has suggested that common personality traits could be linked with reproductive differences.
Conducted in rural villages in Senegal, the study found that women with above-average levels of neuroticism tended to have more children.
Approximately 12 per cent more children were born to those women who showed higher levels of anxiety, depression and moodiness.
Men on the other hand, tended to have more offspring if they were extravert by nature.
Dr Virpi Lummaa from the University of Sheffield led the study, which was published in the Proceedings of the National Academy of Sciences.
She commented: "Our results show that personality predicts family size differently in men and women, and those men with [the] largest families have personality aspects different from the women with the largest families."
Studies such as this could prove to be important in determining the role of the individual in the recent changes seen in fertility patterns around the world, the scientist added.