Tag Archives: twin studies

Nature, nurture, humans, & elephants


First, Goal progress: In bed by 11 p.m. Jan 9, Up at 7:15 a.m. Jan 10. (I’m staying up way too late writing today’s post though, which does not have good implications for tomorrow’s progress report.)

Sometimes when I’m reading completely unrelated books, a common theme will pop up where I least expect it. For instance, a week or so ago I finished Find Your Strongest Life: What the Happiest and Most Successful Women Do Differently by Marcus Buckingham on the recommendation of a friend. In spite of its cheesy cover (sorry friend), it has a few useful insights. One of the most interesting things that stuck out to me was a mention of twin studies in Chapter 12: Tactics for Stronger Kids. (Studies of identical twins have been of casual interest to me for years.) This book references a popular science book that falls strongly on the genetics side of the long-standing nature versus nurture debate:

The truth is that this debate was settled decisively more than a decade ago. And it was settled by a careful study of the personalities of identical twins who were adopted by different families and raised apart, in different homes, by different parents. To answer the nature/nurture question, all you have to do is find out whether the personalities of the twins are more like the parents who raised them or more like the parents who conceived them. And the answer to that question is always the same: the personalities of the twins resemble significantly the personalities of the parents who conceived them, and do not resemble at all the parents who raised them.

Footnote: Judith Rich Harris, “No Two Alike: Human Nature and Human Individuality,” (New York: W.W. Norton and Company), 2006.

The point being, “that each child is blessed with a unique pattern of traits and talents, and that you, the parent, have to try to mold and shape these patterns so that they become useful.” In other words, sometimes kids are born a pain in the ass, and it’s not your fault, but that doesn’t mean you can give up.

Another book that I’m reading is about elephants, and how they are emotionally and psychologically very similar to us. (I’m sure I’ll be following up in another post about the book as I read more of it.) Elephants on the Edge, by G.A. Bradshaw, also mentions twin studies, in Chapter 2: A Delicate Network. But it gives much more credit and leeway to the nurture side of the equation:

To help get to the bottom of the mystery, a series of studies was conducted to examine the habits and personalities of twins separated at birth and raised apart. Results showed that while in some cases, twins exhibit uncanny parallels, other pairs do not seem, except in physical appearance, to be any more related than passing strangers, and their personalities and temperaments could not be explained by either the family tree or their upbringing. Baffling, but as with many other conundrums, answers are neither black nor white, but a little of both biology and experience.

It is not clear from the footnotes which series of studies this is referencing, although there are several in the footnote following the next paragraph:

Research in the area of gene-by-enviroment interactions (GxE) reveals that inheritance and experience intertwine in ways that cannot be statistically separated, much less predicted.

G.A. Bradshaw goes on to say:

The authors of the nearly six hundred-page tome “From Neurons to Neighborhoods,” commissioned by the Committee on Integrating the Science of Early Childhood Development of the National Research Council and Institute of Medicine, conclude that ‘The long-standing debate about the importance of nature versus nurture, considered as independent influences, is overly simplistic and scientifically obsolete.’

The point being, that elephants are much like people: a combination of what they’ve inherited interacting with what they’ve experienced. This has implications for uncharacteristic elephant behaviors in the wild based on trauma.

Interesting things to think about. More on this later.

A twin studies book that I’ve read, if you’re curious about this sort of thing: Entwined Lives: Twins and What They Tell Us About Human Behavior by Nancy L. Segal.