Nature, Nurture, and Identical Twins (with David Bessis)

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4.7 • 4.4K Ratings

🗓️ 19 January 2026

⏱️ 65 minutes

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Summary

Are your genes your destiny? Despite famous studies of identical twins that seem to answer in the affirmative, mathematician David Bessis says: Not so fast. He and EconTalk's Russ Roberts take a deep dive into the "twins reared apart" literature, showing how multiple flaws in those studies undercut their claims about heritability. Bessis demonstrates why the natural experiments are never perfect, and why differences across people in a particular time and place are no guarantee of what will happen to any one human being. They also discuss psychologist Eric Turkheimer's three laws of behavior genetics, emphasizing the role of unique experiences in shaping who we become.

Transcript

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0:00.0	Welcome to Econ Talk, Conversations for the Curious, part of the Library of Economics and Liberty.
0:07.9	I'm your host, Russ Roberts, of Sholem College in Jerusalem and Stanford University's Hoover Institution.
0:13.8	Go to EconTalk.org, where you can subscribe, comment on this episode, and find links and other information related to today's conversation.
0:21.2	You'll also find our archives with every episode we've done going back to 2006.
0:26.7	Our email address is mail at econTalk.org. We'd love to hear from you.
0:36.6	Today is December 22nd, 2025.
0:40.0	Before introducing today's guest, I want to remind listeners to go to eConTalk.org
0:44.8	and vote on your favorite episodes of 2025.
0:48.4	And now for today's guest, mathematician and author David Bessis.
0:52.8	He was last here in October of 2025 discussing his marvelous book, Mathematica.
0:59.0	Our topic for today is a provocative essay from his substack that we will link to.
1:05.0	Title of that essay, Twins Reared Apart Do Not Exist, The Shaky Science The shaky science of genetic determinism.
1:12.6	David, welcome back to Econ Talk.
1:15.6	Hello, Russ. Delighted to be back.
1:17.6	Now, your book Mathematica takes what is for some people a controversial view of mathematics.
1:24.6	Unlike Poch-Carray's quip that, quote, mathematicians are born not made,
1:30.5	you argue that almost anyone can do math if they approach it correctly or more importantly.
1:35.2	The great mathematicians are not uniquely genius-like. They just have an approach that's very
1:42.6	powerful that can be learned by normal human beings,
1:45.5	and it is that approach, that method, and their dogged focus and hard work that yields greatness.
1:51.6	And you're talking in your book about Descartes and Einstein and Growth Addict.
1:56.4	So you do not believe that everything is predetermined by genetics.
	...

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