The truth about gene-environment interaction is in the hyphen
Rebecca Noble is primary author
It’s a typical scene in a preschool classroom: Charlie and Lucy are each happily playing with their own toys when Lucy suddenly eyes Charlie’s toy and wants it, and she wants it NOW. Charlie, sees Lucy’s desire for his toy, doesn’t get possessive but kindly extends it to her. Lucy snatches the toy, declaring “Mine!”, and runs off across the classroom to show her new toy off to her other friends. Charlie doesn’t mind.
In this scene, Charlie displayed what psychologists call prosocial behavior. That is, behavior characterized by concern for, and intention to help, others. Lucy, on the other hand, demonstrated selfish behavior. Why is it that Charlie was able to consider what Lucy wanted and shared, but Lucy thought only of herself? Was it because of the way the two were raised? Alternatively, was there some kind of genetic factor that made Charlie inherently generous and Lucy naturally greedy? As it turns out, the development of prosocial behavior is a matter of both nature and nurture; genes and parenting (Saturn 2014).
Nature and nurture are not in opposition. To the contrary, they work together–constantly. One of the ways nature and nurture are linked is through a hormone called oxytocin.
Oxytocin is a peptide with a wide array of targets throughout the body. It is most well-known for its role in child birth and milk ejection feedback loops, but recent studies reveal the importance of this hormone in the regulation of social behaviors (Donaldson & Young 2008). In humans, natural oxytocin levels are related to feelings of love and trust in intimate relationships both between parent and child and between romantic partners. Furthermore, oxytocin levels are related to empathy and subsequent generosity toward strangers. And, when oxytocin is administered intra-nasally in human subjects, researchers usually observe an increase in generosity, trust, eye gaze, and the ability to infer the emotions of others (Saturn 2014).
The NATURE side
The reason why Lucy and Charlie responded differently in the situation above can be explained in part by genetics. While both Lucy and Charlie have oxytocin circulating in their bodies, they may have different forms of the receptor specific to this hormone. Researchers studying the gene for the oxytocin receptor have identified three different forms, called polymorphisms: AA, AG, and GG. Furthermore, they have demonstrated that the genetic variation between these polymorphisms influences prosociality. Both males and females with the GG polymorphism had significantly higher dispositional empathy and empathic accuracy compared to those with the AA or AG polymorphism (Rodriques et al. 2009).
The NURTURE side
So, if scientific research has identified a gene that can influence our empathy, does that mean Lucy (and her parents) are off the hook for her greedy behaviors? Not quite…
Genetic variability in the oxytocin system may contribute to individual differences in social behavior, but it is by no means the whole story. This genetic variation, is instead, better described as a genetic predisposition—a tendency toward a particular type of behavior whose expression is influenced by the individual’s experience. That is, the environment shapes how genes are expressed (or not).
This is where the influence of parenting comes in according to Dr. Sarina Saturn. Research has shown that parental bonds also significantly influence development of prosocial behavior. Parental affection towards, and soothing and understanding of, children is correlated with an increase in affection given and received, gratitude, altruism, trust, love, interpersonal support, self-compassion, humor, happiness, and satisfaction with life plus better sleep quality and health (Saturn 2014).
But what does this have to do with oxytocin? Well, oxytocin plays a key role in child-parent bonds. When fathers are given oxytocin it induces the release of natural oxytocin in their infants (Weismann et al. 2012). But behavior matters. Affectionate touch of and play with their children trigger oxytocin release in parents, activating brain circuits devoted to caregiving(Feldman 2012). The intimate bonds and activities of parental care increase oxytocin. And oxytocin can, in turn, increase prosocial behaviors.
The truth is that we are not slaves to our genes. Whether children are generous like Charlie or struggle with sharing like Lucy, is a function of BOTH genetic factors such as their particular oxytocin receptor polymorphism AND the nature of their relationship with their parents. It is a constant but changing interaction.
The best bet for increasing prosocial behavior among the human population? Affectionate touch and interactive physical play. These cultivate the hormones that lead to compassionate and altruistic acts. You can build strong social bonds with loved ones and strangers alike. Given the nature of oxytocin, you will find that being good to others is also good for you!
Donaldson, Z. R., & Young, L. J. (2008). Oxytocin, vasopressin, and the neurogenetics of sociality. Science, 322(5903), 900-904.
Feldman, R. (2012). Oxytocin and social affiliation in humans. Hormones and behavior, 61(3), 380-391.
Rodrigues, S. M., Saslow, L. R., Garcia, N., John, O. P., & Keltner, D. (2009). Oxytocin receptor genetic variation relates to empathy and stress reactivity in humans. Proceedings of the National Academy of Sciences, 106(50), 21437-21441.
Saturn, S. (September, 2014). Nature and Nature: Genetic and Parental Contributions to Social and Emotional Traits. Paper presented at the Pathways to Child Flourishing conference, University of Notre Dame, Notre Dame, IN.
Weisman, O., Zagoory-Sharon, O., & Feldman, R. (2012). Oxytocin administration to parent enhances infant physiological and behavioral readiness for social engagement. Biological psychiatry, 72(12), 982-989.
NOTE on BASIC ASSUMPTIONS:
When I write about human nature, I use the 99% of human genus history as a baseline. That is the context of small-band hunter-gatherers. These are “immediate-return” societies with few possessions who migrate and forage. They have no hierarchy or coercion and value generosity and sharing. They exhibit both high autonomy and high commitment to the group. They have high social wellbeing. See comparison between dominant Western culture and this evolved heritage in my article (you can download from my website):
Narvaez, D. (2013). The 99 Percent—Development and socialization within an evolutionary context: Growing up to become “A good and useful human being.” In D. Fry (Ed.), War, Peace and Human Nature: The convergence of Evolutionary and Cultural Views (pp. 643-672). New York: Oxford University Press.
When I write about parenting, I assume the importance of the evolved developmental niche (EDN) for raising human infants (which initially arose over 30 million years ago with the emergence of the social mammals and has been slightly altered among human groups based on anthropological research).
The EDN is the baseline I use for determining what fosters optimal human health, wellbeing and compassionate morality. The niche includes at least the following: infant-initiated breastfeeding for several years, nearly constant touch early, responsiveness to needs so the young child does not get distressed, playful companionship with multi-aged playmates, multiple adult caregivers, positive social support, and soothing perinatal experiences.
All EDN characteristics are linked to health in mammalian and human studies (for reviews, see Narvaez, Panksepp, Schore & Gleason, 2013; Narvaez, Valentino, Fuentes, McKenna & Gray, 2014; Narvaez, 2014) Thus, shifts away from the EDN baseline are risky and must be supported with longitudinal data looking at wellbeing in children and adults. My comments and posts stem from these basic assumptions.
My research laboratory has documented the importance of the EDN for child wellbeing and moral development with more papers in the works see (my Website to download papers):
Narvaez, D., Gleason, T., Wang, L., Brooks, J., Lefever, J., Cheng, A., & Centers for the Prevention of Child Neglect (2013). The Evolved Development Niche: Longitudinal Effects of Caregiving Practices on Early Childhood Psychosocial Development. Early Childhood Research Quarterly, 28 (4), 759–773. Doi: 10.1016/j.ecresq.2013.07.003
Narvaez, D., Wang, L., Gleason, T., Cheng, A., Lefever, J., & Deng, L. (2013). The Evolved Developmental Niche and sociomoral outcomes in Chinese three-year-olds. European Journal of Developmental Psychology, 10(2), 106-127.
Also see these books for selected reviews:
Evolution, Early Experience and Human Development (Oxford University Press)
Ancestral Landscapes in Human Evolution (Oxford University Press)