We use cookies to ensure that we give you the best experience on our website. By continuing to browse this repository, you give consent for essential cookies to be used. You can read more about our Privacy and Cookie Policy.

Durham Research Online
You are in:

The impact of parenthood on physical aggression : evidence from criminal data.

Boothroyd, L.G. and Cross, C.P. (2016) 'The impact of parenthood on physical aggression : evidence from criminal data.', Aggressive behavior., 42 (6). pp. 577-584.


Evolutionary approaches to sex differences in physical aggression weigh the potential benefits of aggression against the likely costs to inclusive fitness, with some authors focusing on the damage physical injury would do to female inclusive fitness, and others on the extent to which success in physical competition may particularly enhance male fitness. This study tested a hypothesis derived from these approaches: that parents would be less physically aggressive than non-parents because of the damage any physical injury would do to their inclusive fitness. Analysis was carried out using the United States federal sentencing records for 1994–1999 (22,344 individuals). The proportion of theft convictions which were violent (robbery; vs. larceny) was significantly greater for men than women (odds ratio 7.7). As predicted, non-parents were significantly more likely to be violent than parents (odds ratio 1.6). Parenthood had a similar effect on relative rates of violence in men and women, although the baseline was considerably higher for men. There was also a significant effect in men of marital status, which interacted with parental status such that parenthood was only associated with a reduction in rates of violence in males recorded as partnered. The results are interpreted in terms of both evolutionary theory and recent work on the hormonal impacts of marriage and parenthood.

Item Type:Article
Full text:(AM) Accepted Manuscript
Download PDF
Publisher Web site:
Publisher statement:This is the accepted version of the following article: Boothroyd, L. G. and Cross, C. P. (2016), The impact of parenthood on physical aggression: Evidence from criminal data. Aggressive Behavior, 42(6): 577-584, which has been published in final form at This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.
Date accepted:14 February 2016
Date deposited:16 February 2016
Date of first online publication:22 March 2016
Date first made open access:22 March 2017

Save or Share this output

Look up in GoogleScholar