Mistaking Parental Influence for Children’s Behaviour

My colleague Dr. Tom Robinson points out that sugar does not actually make children hyper. However, parents who believe that it does see what they expect. When researchers tell parents that their children have consumed sugar, the parents report hyperactive behavior even if the researcher was lying (We researchers are a sneaky bunch).

These sorts of mix-ups are common. Ever heard that if you have a night light in your infant’s room, you are putting your child at risk for myopia? Turns out that near-sighted parents (who of course pass along their lousy-vision genes) are more likely to put lights in their child’s room, and there is no direct effect of the light itself on children’s eyesight.


  1. Dennis says

    Wowza. Keith, do you have a cite on the myopia thing?

    And once more, with feeling, from the drive-by statistician on this board: Folks, correlation is necessary, but not sufficient, for causation.

    • Ken Rhodes says

      I too am fascinated by the myopia thing.

      And Dennis — on this board we are intellectual snobs so we say, mixing our Latin and math notation, “Post hoc !ergo propter hoc.”

      • Keith Humphreys says

        Dennis and Ken: It was in Nature which may be gated but I have edited the post to link to a new story about the study that overturned the prior conclusion by taking parental eyesight into account.

    • Ohio Mom says

      Forgive me these anecdotes. I’d never heard the nightlights-cause-nearsightedness urban legend before but I don’t doubt for a moment that nearsighted parents are more likely to use nightlights.

      I am very nearsighted and have long felt I need extra help seeing in the dark. When I’ve complained to my opthamologist that night driving is uncomfortable for me unless the streets I am traveling are very well-lit, she has always replied that everyone who is nearsighted as we are (for she is also very nearsighted) dislikes driving in the dark.

      More to the point of this post, I didn’t have a nightlight in my son’s room when he was a baby, I had a lamp with a forty-watt bulb plugged into the outlet that responded to the switch by the door. Compared to a nightlight, that’s a searchlight. (He’s 15 now, with perfect vision.)

  2. MobiusKlein says

    Sugar may not make kids ‘hyper’
    But serving them hot coco 10 minutes before bedtime makes sleep harder.

  3. says

    The sugar myth refuses to die. I think a big part of the confusion is that sugar correlates highly with exciting children’s activities in general, such as parties, celebrations, etc.

    From the title of the post though, I thought we were going even more meta, as in describing children’s behavior decontextualized from their home environments.

    • Steven B says

      That’s what I was thinking, and honestly hoping. I have seen far, far too many kids medicated to the eyeballs because their family environments weren’t up to the task of effectively managing development and behavior. I’m not talking about the rare instances of organic, severe disorders either. In fact, I cannot think of a single instance, in hundreds of cases, of a child’s behavior being non-reliant on parenting practices. It all comes down to how much time, effort, and opportunity one has to dig into the situation. Not a matter of blame – just that individualizing the effects of systems to the most vulnerable members is a serious distortion.