Genes 2 Brains 2 Mind 2 Me

The roles of nature and nurture in child development have never been easy to disentangle.  Parents, in particular, seem to know this all too well, when it comes to their own children.  For example, when one of my children throws a tantrum, my wife can be mercilessly quick to point out that “those are your genes at work “.  I for one, can’t help but admire Mother Nature’s sense of justice (or is it humor?) as I’m forced to grapple with an unreconcilable 5-year old.  What can I do?  How can I get some type of optimal gene-by-environment (parenting style) going here?  Afterall, they are MY genes (expressed in said unreconcilable 5-year old) right?  Can I break out of the infinitely recurrent loop of me (my genes) trying to positively interact with my child (also my genes).  What’s a stubborn parent of a stubborn child to do?

In thinking about this, it was great to read a recent article by Lee and colleagues entitled, “Association of maternal dopamine transporter genotype with negative parenting: evidence for gene x environment interaction with child disruptive behavior” [doi: 10.1038/mp.2008.102].  In this article, the team examined how children (4 to 7 years old)  interacted with their mothers during a session where they were induced to cooperate in tasks involving free play with specific toys, tasks involving organizing items in a room and several pencil and paper tasks.  A set of observations were made (through 1-way glass) on aspects of parenting (negative feedback or contact, positive feedback and encouragement, and, total number of maternal commands).

In principle, the complexities of whose genes & behavior is influencing whose in such a situation are vast.  The authors point out that such interactions can be divided into passive GxE wherein children with certain genes (lets say genes for stubborness) may have inherited those genes from parents who exhibit a stubborn (negative) parenting style – hence leading to correlations in child genotype and parenting style.  Alternatively, such correlations can occur when a child (perhaps a stubborn child) evokes negative parenting response from a parent who did not (as my wife claims) transmit said stubborness genes – an example of an evocative GxE interaction.  In this study, the team examined the mother’s genotype at a 40-bp repeat polymorphism in the 3’UTR of the dopamine transporter (DAT) gene.  This is an apt candidate gene, since animal models of DAT loss-of-function show disrupted maternal behavior.

As an initial step, the team evaluated whether maternal genotype was correlated with maternal parenting style.  They found that the 10-repeat allele of the DAT gene was associated with more of a negative style of parenting.  However, the association of the 10-repeat allele of DAT was rather stronger in mothers whose children were categorized as disruptive than among mothers whose children were categorized as compliant – an example of an interaction of the mother’s genotype with her child’s disruptive behavior (which itself may be due to genes inherited by her – and so on – and so on).

Hard to pin down the genetic blame somewhere here.  Maddening actually.  Maddening enough to make dealing with my unreconcilable 5-year old seem a simple and welcoming task.