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Lick Your Kids

What rats can teach us about parenting.

If you have kids you can really mess them up. Seriously. That ass#@!% in traffic, those Neanderthals you work with: all somebody's kids once. But don't despair. You also have the opportunity to make your kids great. Sure they've got your lame-ass genes, but genes aren't everything. The translation of those genes into brain development is shaped by how you interact with them, changing the kind of people they become, and ultimately affecting their chances for success and happiness.

Now I just want to say up front that I don't have kids, so I don't have much to say from personal experience. I do, however, understand neurotransmitters, genetics and brain development. I can't say the right or wrong way to raise your kids, but I am going to describe a simple experiment, and discuss its implications.

We can learn a lot from rats. One beautiful experiment on how rats raise their kids really illustrates the interaction of genes and parenting. To understand this experiment you need to know that there are basically two types of rat mothers: those who lick their babies a lot, and those who don't. Let's call these high-lickers and low-lickers. We could call them good-lickers and bad-lickers, but let's not be so judgmental. (Side note: I'm not sure what happened to the father in these experiments. I think he said he was going out for some cheese and never came back).

The babies of high-lickers turn out a lot better off than the babies of low-lickers. They grow up to be more exploratory, and are more resilient to hardship. They show less of a fear response, and lower stress hormones. And, perhaps not surprisingly, when the girl babies of high-lickers grow up and have kids of their own, they become high-licking mothers themselves. In contrast, the babies of low-licking mothers grow up to be more anxious in new environments, and generally more stressed out. And unfortunately the girl babies of low-lickers grow-up to be low-licking mothers. Thus, in the case of both mothering styles, the behavior is passed on to the next generation of mothers, and will keep being passed on.

So if you want a calm, happy child is it already written in your genes? This is a classic question of nature versus nurture. Is the development of the baby rats guided by their genes or by the mothering style? This is a difficult situation to tease apart, because the children of high-lickers have both the high-licker genes and they get licked a lot. The children of low-licker rats have neither. So scientists did a clever experiment where they took some newborn rats and switched them to different mothers. Babies of bad-lickers went to good-lickers, and vice-versa.

When the babies of high-lickers were raised by low-lickers they ended up stressed and anxious. Maybe being switched at birth is a stressful experience. However, the babies of low-lickers raised by high-lickers ended up with low stress and low anxiety. Interestingly, when the girls grew up they adopted the parenting style of the mother that raised them, not what was in their genes.

In this case nurture wins out over nature, and a large number of experiments have been conducted to understand why. It turns out that being licked by the mother releases a neurotransmitter called oxytocin, which reinforces the relationship between the mother and baby, reduces stress, and changes which part of the DNA gets read. Now oxytocin can't change the genes you have, but it can affect how much those genes get expressed. If the baby doesn't get enough oxytocin early on, then some good genes can get turned off. In addition, oxytocin may also change the development of the amygdala, as well as the hypothalamus. Considering that the amygdala is responsible for generating fear, and the hypothalamus controls the stress response, it is understandable why babies raised by low-lickers are more stressed and fearful.

Being licked by the mother likely has effects on serotonin as well (see my post on boosting serotonin). Serotonin is responsible for proper prefrontal function; so not getting enough serotonin early in life may affect prefrontal development (also see my post on serotonin in the prefrontal cortex). On top of that, serotonin is modulated by our friend oxytocin, so not getting licked enough early in life is a double whammy.

There are numerous other experiments, but too many to describe in one blog post. The point is that kids need attention and physical affection in order to properly develop their neural circuitry.

It might sound like new-age mumbo jumbo (like all that yoga stuff I wrote about), but if you don't pay enough attention to your kids, you may be impacting their brain development. If you aren't loving with them, or don't play with them, or if you don't hug, tickle or kiss them enough when they're little (no need to lick), then you might be turning off genes that you don't want to be turning off, or cultivating growth in the fear and stress regions of the brain. The good news is that, unlike rats, you can have some freakin' self-awareness. You can change your behavior if you want. You can choose to be attentive and loving if you aren't already, even if your parents never were.

My guess is that if you've gotten this far in an article on parenting you're probably a pretty attentive parent (or will be one). So while you can't protect your kids from all the stressful things that might happen to them in life, take solace in knowing that your attention and affection is helping their brains become more resilient to stress and more open to happiness. That's all. Now you can go give them a hug.

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If you liked this post then check out my book - The Upward Spiral: Using Neuroscience to Reverse the Course of Depression, One Small Change at a Time

You may also like my post on The Marshmallow Experiment.

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