Advancing STEM education is a policy objective in many countries. But policies focusing on increasing students’ math skills tend to ignore the importance of comparative advantage in occupational choice. While skills-based comparative advantage has been previously investigated, little is known about the underlying sources of differences in comparative advantages across individuals or their malleability. We show that skills-based comparative advantage is transferred intergenerationally. Parents with a comparative advantage in math (vs. language) skills are significantly more likely to have children with a similar math skill advantage. Parents’ comparative skill advantage is not only a strong predictor of their own STEM choices, but also affects STEM choices of their children.