Two rules of life

I was reading this story headed "Moms Who Don't Breastfeed More Likely to Develop Type 2 Diabetes," and it said pretty much what the headline promised. It does it by reducing mom's belly fat. That got me thinking about other cases where an event changes a little thing with  unexpected results, such as that selecting for tame foxes makes their coat variegated, their tail curly, and their vocalization a bark, by  reducing the generation of adrenaline, and an increase in water temperature is killing some frogs, because it's now just warm enough for some fungus to grow.

And that got me to thinking about the two fundamental insights I have had, and that I have formulated into my two rules of life:

• Rule 1: Everything is more complicated than you think it is. One little thing here affects a big or little thing over there in a way you don't expect. Sometimes it's a good thing; an unexpected effect of legalizing abortion was a moderate influence on the reduction in the crime rate years later, when the unwanted babies would have been prime crime age. Sometimes it's a bad thing; political strife in Congo forces an army to live largely on bushmeat, and chimps and gorillas edge closer to extinction.
• Rule 2: People vary. This is the same as saying people are more complicated than you think they are. Growing up in the same family, brother David becomes a social worker, and brother Ted becomes the Unabomber. Two kids in an abusive household; one becomes an abusive parent, and the other doesn't. Or one kid gets out of the neighborhood, and another doesn't. Or two rich kids, or two anything. People vary along so many dimensions, and our genetics and especially our epigenetics vary in how much cortisol is released, and how one reacts to the cortisol, or oxytocin, or seratonin, or dopamine, or any hormone or neurotransmitter. We can say statistically that, say, experiencing certain things as a child is associated with hitting or not hitting your kids, but we can't say in any individual case, this will cause that, and we know that in some cases it won't; we just don't know which ones.

The policy implication of this is that one size does not fit all. Helping some kids probably means hurting others, and policy making is balancing the helps and hurts.

• If you change the kindergarten age in order to make sure all the kids in the class are old enough for the curriculum, then some kids who were ready younger will have to spend an extra year in the minors. 
• If you teach pretty much only math and reading in 4th grade, the smart kids will be held back. If you don't teach pretty much only math and reading, some kids will not learn to read well enough to follow the class work and will be lost to formal education.
• Kids do better if they have smarter kids in the room, so separating the really smart kids into a single class is good for the one class and bad for everybody else. 
• Any expensive special program, however justified, takes money away from whatever the money would have been spent on. If it is categorical money, then that just means the decision how to divvy up the money was made at a higher level of government.