Genetic distance between countries' populations has been shown to proxy crosscountry differences in cultures and preferences. In a panel of 176 countries from 1970 to 2014, we find that higher genetic distance between two countries decreases their probability of having a trade agreement, even when controlling for geographic distance and other controls. The impact of cultural differences proxied by genetic distance is persistent over time and economically significant: while increasing the geographic distance between two countries by 1% decreases the probability of a regional trade agreement by 1.6%, increasing their genetic distance by 1% decreases the probability by 0.9%.