Barry X. Kuhle Ph.D.

Evolutionary Entertainment

The “Birds and the Bees” Differ for Boys and Girls

Findings from a new study of sex differences in the nature of sex talks.

Posted Nov 28, 2014

An emrassing rite of passage for many American children is the parent-child sex talk. The awkwardness of this “birds and the bees" talk has been hilariously depicted in many movies, perhaps best so in the 1999 teen sex comedy American Pie:


Using evolutionary psychological theories as a guidepost, in a forthcoming publication in Evolutionary Behavioral Sciences with my undergraduate RAs and developmental psychologist Dawn K. Melzer, I explored the content of communications that parents have with their children about sex (Kuhle et al., 2014, June 30). Our focal question was whether parents tell certain things about sex to their daughters and other things to their sons.  

The Daughter-Guarding Hypothesis

Most prior research on such talks failed to carve nature at its joints (Plato & Scully, 2003) by exploring the differential functions that parental sex-talks may serve for sons and daughters. We tested six sex-linked predictions about the content of parental sex-talks and other messages that parents communicate to their children. Our predictions were derived from the daughter-guarding hypothesis which posits that, “parents possess adaptations with design features that function to defend their daughter’s sexual reputation, preserve her mate value, and protect her from sexual victimization” (Perilloux, Fleischman, & Buss, 2008, p. 219). We reasoned that parents may attempt to guard their daughters’ sexualities through strategic communication about sex because, relative to ancestral sons, ancestral daughters incurred greater reproductive costs (Buss, 2003; Perilloux et al., 2008; Trivers, 1972) from:

  1. an untimely or unwanted pregnancy
  2. rape and other forms of sexual victimization
  3. damage to their long-term mate value as a result of early, pre-marital, short-term (i.e., casual) sexual experience

Daughter Guarding Examples

Examples of daughter-guarding can be found in anthropological, psychological, and popular culture outlets. Anthropologist Mark Flinn (1988) coined the term “daughter guarding” and documented examples of it by rural Trinidadian fathers who restricted their daughters’ movements, forced them to take chaperones, and threatened men who came to visit their daughters. In support of their daughter-guarding hypothesis, evolutionary psychologists Carin Perilloux, Diana Fleischman, and David Buss (2008) found that parents of U.S. college students were more likely to control their daughters’ than sons’ mating decisions, mate choice, and sexual behavior and reported greater upset over their daughters’ than sons’ sexual activity. On a lighter, popular culture note, comedian Chris Rock, whose stand-up material often reflects a sophisticated grasp of evolved psychological sex differences (Kuhle, 2012; see also this blog series), riffed about the importance of daughter-guarding in this bit from his 2004 HBO special Never Scared:

Predictions Derived from the Daughter-Guarding Hypothesis

Given previous theory and findings, we predicted that daughters would be more likely than sons to report receiving a parental sex talk and other parental messages that encouraged:

  • abstinence (prediction 1)
  • being discriminating in allocating sexual access (prediction 2)
  • deterring, inhibiting, and defending against sexual advances (prediction 3)

 We also predicted that daughters would be more likely than sons to report receiving messages:

  • to not emulate depictions of sexual activity (prediction 4)
  • that defined when they were old enough to date (prediction 5)
  • that curtailed contact with the opposite sex (prediction 6)


We administered an online questionnaire that tested these six sex-linked predictions. Our participants were undergraduates from a Northeastern U.S. Jesuit university (n = 226) and young adults recruited through Facebook (n = 391).


With all six predictions confirmed, the results from this study support the daughter-guarding hypothesis (Perilloux et al., 2008) from which the predictions were derived. As expected, daughters more so than sons received a parental sex talk and other parental messages that encouraged abstinence, being discriminating in allocating sexual access, and deterring, inhibiting, and defending against sexual advances. Also as expected, daughters were more likely than sons to receive messages to not emulate depictions of sexual activity, that defined when they were old enough to date, and that curtailed their contact with unrelated members of the opposite sex.  It appears that our participants’ parents were more focused on guarding the sexuality of their daughters than their sons.

Although daughters were significantly more likely than sons to receive each of the predicted messages about sex from their parents, these findings are not due to daughters being more likely to receive any and all messages about sex. Sons were significantly more likely than daughters to be told to “have fun” and equally likely as daughters to be told other messages (e.g., “sex should be enjoyable”).  

Modern day American parents appear to socialize children in ways that fostered ancestral reproductive success through the communication of sex-linked birds-and-the-bees talks and messages.

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Buss, D. M. (2003). The evolution of desire: Strategies of human mating (revised edition). New York: Basic Books.

Flinn, M. V. (1988). Parent-offspring interactions in a Caribbean village: Daughter guarding. In L. Betzig, M. Borgerhoff Mulder, & P. Turke (Eds.), Human reproductive behaviour (pp. 189-200). Cambridge: Cambridge University Press.

Kuhle, B. X. (2012). It’s funny because it’s true (because it evokes our evolved psychology)Review of General Psychology, 16, 177-186.

Kuhle, B. X., Melzer, D. K., Cooper, C. A., Merkle, A. J., Pepe, N. A., Ribanovic, A., Verdesco, A. L., & Wettstein, T. L. (2014, June 30). The “birds and the bees” differ for boys and girls: Sex differences in the nature of sex talks. Evolutionary Behavioral Sciences. Advance online publication.

Perilloux, C., Fleischman, D. S., & Buss, D. M. (2008). The daughter-guarding hypothesis: Parental influence on, and emotional reactions to, offspring's mating behavior. Evolutionary Psychology, 6, 217-233.

Plato, & Scully, S. (2003). Plato's Phaedrus. Newburyport, MA: Focus Pub./R. Pullins Co.

Rock, C. (Executive Producer). (2004). Chris Rock: Never Scared [DVD]. HBO.  

Trivers, R. L. (1972). Parental investment and sexual selection. In B. Campbell (Ed.), Sexual selection and the descent of man: 1871 - 1971 (pp. 136-179). Chicago: Aldine.

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Copyright © 2014 Barry X. Kuhle. All rights reserved.

Disclaimer: The views expressed in this blog do not necessarily reflect the views of Psychology Today and the University of Scranton, or my friends, family, probation officer, gut bacteria, darkest thoughts, and personal mohel.

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