Significance This paper shows that cultural factors play a key role in shaping the genetic structure in sorghum. We present molecular evidence of close associations between sorghum population structure and the distribution of ethnolinguistic groups in Africa. We show that traditional seed-management practices, which have played an important role for survival and expansion of agropastoral groups in the past, still are remarkably resilient to threats to human security. We argue that efforts to strengthen African sorghum seed systems are more likely to be successful when building on, rather than seeking to replace, existing traditional seed systems and landraces.