In genetics, heterosis describes how crossbreeding produces offspring with greater fitness than their parents. We propose a socioeconomic heterosis hypothesis: does genetic diversity at the individual level benefit economic success? Using UK Biobank data (N=488,152), we find that people with higher genome-wide heterozygosity perform better in modern societies. Greater heterozygosity is positively linked to education, income, leadership, height, and ownership of a home and car. A one standard deviation increase corresponds to about 0.75% higher income and modest gains in schooling and assets. Results are robust to additional controls and corrections for multiple testing, with no effects on migration, diabetes, or neuroticism. Effects rise steadily across the observed range and are stronger for men, suggesting sexual selection. Because heterozygosity is fixed at conception, our findings reveal an underappreciated endowment shaping human capital, wealth accumulation, and inequality.