Just a cursory search on Google for the 'heritability of lifetime income' leads me to this from a study in Finland:
> For example, Björklund and Jäntti (2012) estimated using Swedish data that shared environmental and genetic factors explain 40–60% of inequality in a number of productive traits, including cognitive and non-cognitive skills, schooling and long-run earnings.
Assuming that this paper holds up, then at around half of lifetime earnings would be attributable to environment.
Also, speaking purely of heritability factors is a little reductive. Two parents that lack a particular phenotype that, say, is fit for wage growth in our contemporary economy, may have offspring that does. Similarly those fit to succeed in the economy today, may not be in the future if the stressors change.
I'm not sure this holds up to scrutiny. My limited understanding of epigenetics means that social factors and genetic factors are not so easily separated, we'd need significantly more generations of data to show that.
If you were familiar with the data, you wouldn't make statements like that, because heritability is a population statistic, not a constant. It varies significantly between populations, to the point where you can't make claims about it without controlling for the population you're studying.
For instance, we could say that the heritability of intelligence among the children of suburban Chicago families in a particular income bracket is 70%, but not that the heritability of intelligence in general is 70%.
If you were familiar with the data, you wouldn't make statements like that, because heritability of intelligence is largely the same across all population studied so far, and universally high. There are exceptions, e.g. Scarr-Rowe effect is most likely real, but it only seems to work on very low end of SES range, which is virtually unseen in today's America, even at the lowest end of what counts as poverty.
Via what mechanism are we testing? Did we send some kids through a good upbringing and some to a bad one in a randomized controlled way, or did we just take a survey and assume intelligence was passed down through genealogy instead of upbringing?
> Via what mechanism are we testing? Did we send some kids through a good upbringing and some to a bad one in a randomized controlled way, or did we just take a survey and assume intelligence was passed down through genealogy instead of upbringing?
The most informative studies in this area are usually of twins-separated-at-birth, but the datasets aren't very large.
Scarr's original twin study was done in Philadelphia. Seems strange to discount the Scarr-Rowe effect as not existing in the US at all when it was originally found there in the first place.
Scarr’s original study was done over 50 years ago on kids who grew up in pre-Civil Rights America. That level of deprivation is, as I’ve said, virtually unseen in today’s America. Recent studies usually fail to replicate it on more recent experimental data.
We know it holds up to scrutiny, because the epigenetics excuse, constructed without the information supply needed to support it, doesn't hold up to scrutiny.
Sure; but this trend doesn’t rely on upbringing alone.
The children of two collage graduates have collage graduate genes and a collage graduate upbringing. It’s no surprise they’re (we’re) overrepresented in collages.
People aren’t dumb because they got the stupid gene (barring deformity that does real brain damage). They’re dumb because they were taught to be.
The are large social circles that being smart is a bad trait. There are social circles where there is little opportunity to learn as well. There’s little differentiation between baby brains and epigenetic traits aren’t set in stone by parentage, though upbringing will have a strong effect throughout life.
You don’t inherit intelligence, you get taught to throw it away or not based largely on environmental factors, including how your parents raise you.
> You don’t inherit intelligence, you get taught to throw it away or not based largely on environmental factors, including how your parents raise you.
You're glossing over the role of other personality traits in success. And yes, environmental factors are hugely important to those as well, but often in complex ways.
For example, food insecurity during childhood has an enormous impact on an individual's ability to delay gratification. While there is certainly quite a bit that parenting can do to make that even worse, there isn't a lot that can be done to make it better.
While this is a cynical response, it's kind of true. Many progressive causes are doomed, because almost everything is shockingly heritable. If you try to "break cycles" that actually emerge from acyclic causal networks, at best you will accomplish nothing and at worst you will introduce additional inefficiencies and suffering (more likely).
The one thing you can do that won't be harmful is basically funding genetic selection research, e.g. lowering the cost of IVF embryo selection. This is relatively morally palatable (esp. compared to e.g. eugenics) but will actually have the desired effects.
