The Henderson laboratory has published new work in eLife investigating the effect of natural genetic diversity on the recombination process that occurs during sexual reproduction. They screened Arabidopsis lines from across the world for their effects on recombination and found evidence for extensive genetic modification. One surprising effect was that chromosome regions with genetic differences showed higher levels of recombination than identical regions, which was contrary to expectation. Using genetic analysis they show that this phenomenon involves a mechanism called crossover interference, whereby recombination events communicate to one another along the length of the chromosomes. Together this reveals a new and unexpected effect for genetic diversity on the recombination mechanism.