Your environment is the sum of your experiences

Tyler Cowen asks whether children brought up in the same family share the same environmental influences and then concludes “Maybe not”. Maybe not? Definitely not.

He’s referring to a 1987 paper with a recent commentary:

For most psychological characteristics, correlations for adoptive ‘‘siblings’’ hover near zero, which implies that the relevant environmental influences are not shared by children in the same family. Although it has been thought that cognitive abilities represent an exception to this rule, recent data suggest that environmental variance that affects IQ is also of the nonshared variety after adolescence.

My favorite part of the paper is the section which discusses how siblings represents a non-shared environment for each other.  For instance my sister grew up with a slightly younger brother and I grew up with…a slightly older sister, which is a somewhat different proposition.

Remember that you are the sum of the experiences of your life, and you and members of your family will never have the same life as you. Little events build up to become big influences on a life. In one experiment, scientists took genetically identical mice and put them in a Big Brother-esque box in order to watch how their behavior changed with time. Tiny, potentially random differences in life snowballed into large differences in personality. Mice that explore a little at the beginning of their life are soon roaming widely across their world later in life, and mice that have no need to venture out at the beginning of their life never will later on.

To take a simple example from my life: when I was growing up, my mom started biking to work around the time that I moved to a new elementary school. My school was in biking distance so obviously I wanted to bike to school just like my mom biked to work. The habit stuck and I’ve biked everywhere since then. By the time my siblings were old enough to be able to bike to school, my mom’s biking had been curtailed and the novelty had worn off. Neither ever biked to school and still don’t. This all means I grew up in a bike-based environment and my siblings grew up in a car-based one – very different. It’s a just-so story but it illustrates the magnification of tiny events that become our divergent lives.

Basically: learning happens.

Americans: outliers among outliers

Researchers found that Americans perceive the line with the ends feathered outward (B) as being longer than the line with the arrow tips (A). San foragers of the Kalahari, on the other hand, were more likely to see the lines as they are: equal in length. Subjects from more than a dozen cultures were tested, and Americans were at the far end of the distribution—seeing the illusion more dramatically than all others.

More recently psychologists had challenged the universality of research done in the 1950s by pioneering social psychologist Solomon Asch. Asch had discovered that test subjects were often willing to make incorrect judgments on simple perception tests to conform with group pressure. When the test was performed across 17 societies, however, it turned out that group pressure had a range of influence. Americans were again at the far end of the scale, in this case showing the least tendency to conform to group belief.

It is not just our Western habits and cultural preferences that are different from the rest of the world, it appears. The very way we think about ourselves and others—and even the way we perceive reality—makes us distinct from other humans on the planet, not to mention from the vast majority of our ancestors. Among Westerners, the data showed that Americans were often the most unusual, leading the researchers to conclude that “American participants are exceptional even within the unusual population of Westerners—outliers among outliers.”