There is surprisingly good evidence in favor of the contrarian views of medicine and parenting, but I'm not quite convinced. Yes, the orthodox views are full of holes. And yes, the statistics for the contrarian views seem pretty solid, with lots of studies estimating effects around zero. But there are two interpretations of these zeros.
One is that there is no effect. The other is that there are both positive and negative effects - maybe large effects - that roughly cancel each other out. And for both medicine and parenting, the latter interpretation makes a lot more sense.
Start with medicine. Modern techniques have clearly saved a lot of lives. If memory serves me, survival rates for premature babies have skyrocketed from 10% to 90%. You probably know someone who is alive today as a result. I thin my twins qualify.
But you probably also know quite a few cases of people who died prematurely as a result of unnecessary medical treatment. Alex Tabarrok writes that:
More people die from medical mistakes each year than from highway accidents, breast cancer, or AIDS and yet physicians still resist and the public does not demand even simple reforms.
My grandpa was probably one of the the mistakes. He got elective surgery on his knee, and never came out of anesthesia.
From this perspective, low estimates of the benefits of medicine cease to be counter-intuitive. You don't have to deny the medical miracles you've witnessed. You only need to remember to average them in with all the disasters.
The same goes for parenting. We all know kids who let their parents plan their lives for them. Maybe it's 100% genetic, but that's a stretch. It's more plausible to acknowledge that these pliable kids exist, but point out that they're only half the story. We also all know kids who heard their parents' plans for their future, and did exactly the opposite just to spite them.
Rebelling against pushy parents is fun! Would I cringe at the sound of televised sports and roll my eyes at antique cars if my dad hadn't been in love with both? I doubt it.
Bottom line: Contrarians often assert that medicine and parenting "don't matter." But that is only one interpretation of their empirical findings. My interpretation is more intuitively plausible, and the data is equally consistent with it.