The Heritability of Everything

The gold standard in heritability estimates is the twin study, which involves looking at identical and fraternal twins, raised together or apart. This allows the cleanest test of decomposing the variance in observed traits into genetics, shared environment (factors equally affecting all children raised together), and non-shared environment (everything else, including random noise) contributions.

Generally it is assumed that the effect of parenting is equated with the shared environment, though there is clear evidence that parenting can differ substantially between siblings of the same parents and account for a significant fraction of non-shared environment, and the shared environment by definition also captures e.g. the neighborhood in which you grow up. Generally there are many caveats to apply to heritability estimates, particularly that they are only defined within a given population and may not apply as well in extreme cases, but nonetheless they are our best estimates as to the effects of genetics, and the effect is undeniably large.

An extremely ambitious meta-analysis of all twin studies was published in May 2015, reporting heritability estimates from 2,748 studies featuring over 2 million twin pairs, encompassing virtually every published study to date. The researchers have made a data visualization tool available if you wish to dig down into various aspects of the study, though it’s fairly opaque if you’re not familiar with the field’s jargon.

Across very broad domains of health outcomes, almost everything falls within the 40-60% heritability range, with cancer as a representative example being 46% heritable. Similarly, neurological variables show about 50% heritability (with little shared environment involvement), while cognitive and psychiatric outcomes are similarly heritable, but also have a nearly 20% shared environment component. Social values appeared to be 31% heritable, but shared environment played nearly as big a role at 27% explained. Similarly, social interactions were 32% heritable, with a somewhat smaller shared environment component of 18%.

Drilling down into more specific categories of interest, intellectual functions broadly were highly heritable at 67%, while more specific executive function metrics were 51% heritable with a high 24% shared environment contribution. Mood disorders were highly variable, from bipolar being 68% heritable to depressive episodes being 34% heritable. Height and weight showed 63% heritability, with relatively large 30% and 20% shared environment contributions respectively. The more specific values and social variables were mostly in line with the overall findings. Tendency towards religion and spirituality was 31% heritable with an even larger 35% shared environment component. Basic interpersonal interactions were similar, with 30% heritability but 36% determined by shared environment.

To summarize, basic variables in terms of intelligence, height, and weight are primarily determined by the genetic contributions. Most health and psychiatric outcomes fell somewhere in the middle, but still showed roughly half of variance explained by genetics. Variables relating to fundamental values (e.g. religion, politics) and social interactions (e.g. emotional intelligence, relationships) were by far the most malleable traits, with roughly equal contributions from genetics and shared environment.

Discussing Tricky Stuff

When I’m discussing something hard, especially over the internet, I try to be careful about:

  1. Searching for and explicitly talking about tradeoffs, even when one option seems like a clear overall win to me.
  2. Trying to keep the ratio of positive to normative statements very high.

I don’t think these points are either necessary or sufficient for intellectually honest discussion, but I think they help. And when other people aren’t doing these things, I find it harder (in the sense of more cognitively effortful) to learn from them. 

With respect to the first point, I don’t think it’s very helpful, if it all, to emphasize tradeoffs that “seem reasonable”, but that the person presenting the idea doesn’t actually think are in play.

I imagine this post would be better with examples, but I won’t include any for now. My plan is to write some blog posts soon about object-level stuff and try to follow my own advice.

What Has Changed my Political Beliefs

I think it’s safe to say that political beliefs are one of the most sticky types of beliefs we commonly hold. By some measures partisan polarization is at record highs for the modern era (though these figures are also debated). Politics are also beliefs that provoke some of the strongest arguments between differing viewpoints, and the strongest consolidation among shared viewpoints. Eliezer warned us to be particularly careful when grappling with these ideas.

But, as good rationalists, all of our beliefs should be subject to updating upon receiving further information – and when I look at my political beliefs over the years, I see that they have indeed changed, in some ways massively, in other ways slow and subtly. I thought it would be an interesting to lay out what the drivers of these changes were, as a case study in the art of changing one’s mind.

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Summary of How To Talk So Kids Will Listen & Listen So Kids Can Talk

How To Talk So Kids Will Listen & Listen So Kids Can Talk is a parenting / communication book written by Adele Faber and Elaine Mazlish. While this book is specifically intended for parents to have better relationships with their children, the vast majority of the advice contained within applies universally to all interactions, and I have written this summary specifically to abstract away from parent-child relationships. I consider the first chapter alone better at helping people internalize the principles behind nonviolent communication than Rosenberg’s entire book. HTTSKWL is currently by far my most highly recommended communications book, and because it is appealing to parents and children it is a remarkably easy read.

Note that unlike most books, this one contains a very high ratio of exercises and prompts and anecdotes relative to its advice. The authors recommend going through the book slowly, and doing all the exercises. This summary will only contain their explicit instructions – I highly recommend buying a copy of the book and completing it. The many specific example conversations will give a much better understanding of the principles I lay out here than I can convey in a summary.

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For ages, I’ve been hearing about how important “boundaries” were, and I’ve never been quite sure what people even meant by the word. A while back I went to parenting discussion about boundaries, and I think I finally figured out what the word means! (To me, that is. I’m not sure everyone agrees on how boundaries work.)

The word “boundaries” always bugged me because it was vague, and seemed to include some assumptions that I wasn’t sure I agreed with. One such assumption was the idea that good boundaries were bright lines. (Now I think it depends.) “Boundaries” also sounded like the sort of thing I was supposed be very careful to respect, more so than mere “preferences”, and I was confused about exactly why.

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Some Indian Recipes

These won’t be particularly well-formatted, and I don’t have any pretty pictures to go with them at the moment, but I’ve had a few requests over the years for the Indian recipes I regularly cook, so here they are!

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A Theory of Economic Development

If I had to give the Most Underrated Professor Award to anyone I studied under, it would easily have to be Professor Meir Kohn. His work falls squarely outside the paradigm of mainstream economics, which (coming from me anyway) could not be a higher compliment – yet also makes it difficult to get traction inside the field. Kohn himself wrote a great essay contrasting the mainstream paradigm of Samuelson and Hicks with the lineage of more qualitative thinking descended from Adam Smith, including fields like economic history and new institutional economics and public choice theory among others.

He has been working on a theory of economic development for two decades now, and in my opinion it appears to be substantially correct. He first composed an unpublishable opus about European economic development from 1000-1600, which I read in its entirety. Then he wrote a more condensed version, where he applied the theory to China as well as Europe, which is likely going to be published in the next couple of years. In private correspondence, he has indicated that he and his students are now applying the model quite successfully to analyzing other economies throughout history.

The first chapter of his first opus contains the best description of his overall model I have yet read. Because I hold it in high regard, believe it to be fundamentally true, and I refer to it often, I am posting my summary of it below. All errors and omissions are mine.

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(Partial) Summary of A Theory of Moral Sentiments

Adam Smith is best known for being the father of modern economics with the publishing of his magnum opus The Wealth of Nations. Far fewer people know about his second most famous book A Theory of Moral Sentiments (which, incidentally, is where the term “invisible hand” actually comes from). While the book is nominally about moral philosophy, I think it would be more accurately described as a work of psychology: Smith is trying to explain how morality arises from the workings of our minds. Much in the same way that The Wealth of Nations still seems surprisingly insightful today, I posit that A Theory of Moral Sentiments accurately described aspects of human psychology that were not appreciated until much later. I enjoyed listening to the EconTalk book club on ToMS as well, if you want to have a lively discussion with lots of background and historical context.

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Understanding Body Language, Touch, and Appearance

When it came to understanding body language, fashion, all of that kind of stuff, I used to be a typical clueless nerd. I didn’t perceive it, and I didn’t think it really mattered.

I know better now.

It matters. A lot.

Over the years I have seen a lot of objections to learning to perceive this kind of thing on a conscious level – but notably these objections tend to come from people who already know how to do it! For those of us who never learned how to perceive these things by default, there is little choice but to go through the usual conscious incompetence route at first, and I wholeheartedly support any geeks who want to learn how to get better at the things that everyone else already does.

To that end, I have written up notes on body language, touch, and appearance, which systematize most of what I know about these important social variables, and I want to make them available to anyone who wishes to learn this stuff. It can be a challenging and even overwhelming road at first, but I think it’s an incredibly important life skill. Remember that social interaction is a positive sum game. You can have increasing social success and other people will find you more fun to be around!

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New Perspectives on IFS

I did some IFS with a friend last night around his nail-biting, an area where he hadn’t gotten much traction working on his own.

Early in the process, when he expressed some judgements about the nail biting, I clarified that I wasn’t interested in getting him to stop biting his nails if we couldn’t first find a better way to meet whatever need was currently being met by nail biting.

I assumed the nail biting was serving an important purpose.

Assuming that neurotic-seeming behaviors may be serving important purposes is part of the IFS instructions, so I’ve been saying stuff like that since I’ve started doing IFS. But saying it used to feel more like going through the motions. I’m not quite sure what I mean, because I really didn’t want to get rid of or change parts without their consent. It feels different now, though.

I trust that people’s internal ecosystems make quite a lot of sense.

On a related note, I haven’t had much desire to do IFS on myself recently. Or to have others do it on me. Mostly because I assume that I’ve internalized these processes enough that if things haven’t found a way to shift on their own in IFS-y ways, there’s a good reason they haven’t.

I’m still very open to conversations where I explore my psychology around a thing, but I want them to feel more organic.

I’m also more inclined to just try to give myself what I want instead of changing what I want, even if I sense that I want it in part because I’m hurt in some way. The example that came up most recently was thinking about how I often get angry after we hire cleaners, since they don’t do it exactly how I’d want them to. I think the getting angry is a bit of my own craziness, but these days I’m somewhat more inclined to actually get what I want anyway, instead of “healing” it.

This shift fits pretty well with the idea that paradigms work best as scaffolds instead of permanent structures. So, my IFS scaffold is pretty dismantled by now.

Probably not my clearest post ever, but I’ll leave it at that.