Top 10 Replicated Findings From Behavioral Genetics

The classic paper from Robert Plomin, John C. DeFries, Valerie S. Knopik, and Jenae M. Neiderhiser.

"In the context of current concerns about replication in psychological science, we describe 10 findings from behavioral genetic research that have replicated robustly. These are “big” findings, both in terms of effect size and potential impact on psychological science, such as linearly increasing heritability of intelligence from infancy (20%) through adulthood (60%).

Four of our top 10 findings involve the environment, discoveries that could have been found only with genetically sensitive research designs. We also consider reasons specific to behavioral genetics that might explain why these findings replicate."

James Thompson has a good post which summarises the theses: "10 Replicants in Search of Fame", with an endearing introduction centred around Philip K. Dick's aphorism:

Reality is that which, when you stop believing in it, doesn’t go away.

I used to think that as the genomic revolution rolled on, social scientists everywhere would wake up, smell the coffee .. and proceed to revolutionise their disciplines.

That was until I encountered Conley and Fletcher.

The Economist: intelligent stupidity about migrants

The Economist says:

"Tens of thousands of asylum-seekers flowed towards Germany by rail, bus and on foot, chanting “Germany! Germany!”, to be welcomed by cheering crowds. Germany is showing that old Europe, too, can take in the tired, the poor and the huddled masses yearning to breathe free. It says it can absorb not thousands, but hundreds of thousands of refugees.

Such numbers will inevitably raise many worries: that cultures will be swamped by aliens, economies will be overburdened, social benefits will have to be curbed and even that terrorists will creep in. Anti-immigrant parties have been on the rise across Europe. In America, too, some politicians want to build walls to keep foreigners out.

Yet the impulse to see migrants as chiefly a burden is profoundly mistaken. The answer to these familiar fears is not to put up more barriers, but to manage the pressures and the risks to ensure that migration improves the lives of both immigrants and their hosts."

All of this would be very compelling if the social capital represented by the incomers was at the same level as or, better, superior to that of the present northern European incumbents. The Economist thinks (or pretends to think) this is a non-issue .. but unfortunately, it's not.

This is what the UCL guy who looked at the evidence had to say.

Digit ratios

Dr James Thompson writes about digit ratios and feminists, a recent news story.

The statistic in question is the length of your second digit (index finger) divided by the length of your fourth digit (ring finger). This is normally less than one, indicating you have a longer ring finger (digit 4). Here are scans of the author's right hand - palm up - and his wife's, with all relevant data points indicated.

The idea is this:

"It has been suggested by some scientists that the ratio of two digits in particular, the 2nd (index finger) and 4th (ring finger), is affected by exposure to androgens e.g. testosterone while in the uterus ..."

A low ratio (e.g. 0.94) suggests you are more likely to be high in testosterone, male and black. A high ratio (e.g. 0.98) suggests lower testosterone levels, female and caucasian or east asian. See here for details.

The article Thompson discusses looks, however, at how all this might illuminate the paradox of feminism:

"The feminist movement purports to improve conditions for women, and yet only a minority of women in modern societies self-identify as feminists. This is known as the feminist paradox."

Why might this be?

"Evolutionary psychology observes that the basic pattern of psychological differences between the sexes can be explained by their having essentially different innate adaptations associated with, most importantly, women investing considerably more resources into offspring through pregnancy and breast-feeding (e.g., Buss, 2012). Males are more aggressive and risk-taking on average, because these traits have paid off historically in terms of increased fitness, given that male-male aggression and risk-taking in the pursuit of resource acquisition have led to more offspring. This would thus explain why males tend to dominate professions where these traits are necessary for success, such as in the military, business, politics and even crime, where competition is high. Females are on average more sociable and empathic than males, because caring for offspring and negotiating social relations that promote their survival until they reach reproductive age ensured that the mother’s genes live on. Hence women dominate professions where these traits are maximally valued, such as teaching, social work, and in human and veterinary medicine (Lippa, 2010). ...

"Another possible explanation of why feminism represents a minority position amongst women is therefore that the activists who shape feminist attitudes and beliefs are themselves generally more physiologically and psychologically masculinized than is typical for women (Wilson, 2010). This might for example explain their belief in sex-role interchangeability, as they may perceive the behaviors and interests of sex-typical women as incomprehensible and at variance with their own more masculinized preferences in terms of child-rearing and status-seeking. This might then lead them to infer that women in general have been manipulated to become different from themselves by external forces, as embodied by notions of social constructions or gender systems ..."

And so they did the 2D: 4D finger length ratio test at a feminist activists' conference. Their account is quite amusing.

"We therefore recruited our sample directly from the operational definition, that is, attendees at a feminist conference in Sweden. This public one-day event was advertised through posters, flyers, and social internet media, and featured some 20 talks and lectures in several parallel sessions, presented by political and other interest organizations. In the conference hall we set up a table and a sign saying (translated from Swedish) “Answer a few questions and image your hands in exchange for fruit or candy. Your participation is anonymous.” We surmised that any mention of feminism, and the possible connection between feminism and biomarkers in particular, would have deterred attendees from contributing. In order to maximize participation, therefore, we did not ask them if they self-defined as feminists, and did not disclose the purpose of the study.

"In total, 35 attendees participated in data collection over the course of the whole conference day, mostly when moving between rooms, in exchange for items of fruit or candy. To ensure anonymity no biographical information was collected, and sex and age were assessed visually (20–45 years). The total number of attendants was estimated at ∼100 over the day and the female-to-male ratio to ∼2/3. Twenty-five of the respondents were female and hence were eligible for inclusion in the analyses, which means that our sample included ∼35% of the female attendees."

And after all the fruit and candy had been distributed, what were the results? Their diagram below shows: the reference female population, the reference male population and the sample from the feminist conference. The mean 2D:4D figures, read off the chart are as follows: mean female = 0.992, mean male = 0.969, mean feminist = 0.95. Yep, the feminist women scored more masculine than the average Swedish man. This may explain something about Sweden.

The x-axis increment is 0.0135

It's hard to obtain large population studies which are tightly controlled for ethnicity, at least via Google, so I don't know where Clare and myself lie on the British/Caucasian spectrum. However, lower ratios predispose males at least to higher risks of prostate cancer and autism spectrum disorders, as you can see from this table. I think this is compatible with what my 23andMe results already suggested.