Money

Study Claims 45 Percent of Investing and Savings Behavior Genetically Determined

My First Million · I put 80% of my money in the S&P after Howard Marks told me not to · May 11, 2026

My First Million

I put 80% of my money in the S&P after Howard Marks told me not to

"The results that he found was basically—and concluded was that 45% of savings and investing patterns and behaviors was genetic, which I find to be astounding."

A Swedish researcher named Heinrich studied 30,000 sets of twins using Sweden's twin database and wealth tax records to analyze investment biases including excessive turnover, home bias, and disposition effect. The study concluded that nearly half of financial behavior is genetically predetermined, though the research also found that working in finance—experiencing actual losses and gains—was the only factor beyond genetics that meaningfully improved investment outcomes.

About this episode

In this episode of My First Million, hosts Sean Puri and Sam Parr explore how genetics shape financial behavior and discuss paradigm shifts in AI deployment and corporate structure. The conversation opens with a Swedish twin study claiming 45% of investment behavior is genetically determined, analyzing biases like excessive trading, home bias, and refusing to sell losers across 30,000 twin pairs. Puri and Parr debate whether such research is useful or limiting, with Parr favoring productive placebos over deterministic conclusions. They examine investor Mohnish Pabrai's transformation after personality testing revealed his ideal zone as solo, competitive, numbers-based work, leading him from mediocre entrepreneurship to investment success. The discussion shifts to Jack Dorsey's radical restructuring at Block, where AI becomes the decision-making brain and humans serve as information nodes—inverting traditional corporate hierarchy. They cover Citrini Research's controversial prediction that AI productivity gains will collapse the economy by gutting white-collar jobs and consumer spending, triggering major market sell-offs. The episode explores YC's Request for Startups including aesthetic data centers to combat NIMBY resistance, drone swarm defense as the new warfare paradigm, and AI-powered personalized medicine. Dramatic examples include former GitHub CEO Nat Friedman allowing AI to control his Tesla route for supplement purchases and GitLab CEO Sid reportedly using AI to treat his cancer with encouraging results. The hosts conclude that technological ground is shifting again, similar to past waves from social networks to marketplaces to crypto, with hard tech, defense, and AI management representing the new frontier.

Key takeaways

Swedish twin study of 30,000 pairs concluded 45% of investing and savings behavior is genetically determined across six major biases.
Investor Mohnish Pabrai's personality assessment revealed optimal zone as solo competitive numbers-based work, leading him to abandon entrepreneurship for investing.
Jack Dorsey restructuring Block so AI serves as company brain making decisions while humans function as information-feeding nodes.
Citrini Research predicted AI productivity gains will collapse economy by eliminating white-collar jobs and destroying consumer spending cycle.
GitLab billionaire CEO Sid reportedly using AI-driven analysis to treat his cancer with encouraging results though not yet cured.
Former GitHub CEO Nat Friedman allowed AI agent to autonomously reroute his self-driving Tesla to purchase supplements after analyzing his health data.
YC Request for Startups prioritizes aesthetic data centers to overcome NIMBY resistance and drone swarm defense as new warfare paradigm.