Archaeological and anthropological data concerning two children’s burials representing the early horizon at Boldyrevo-4 kurgan 1, Orenburg Region, excavated in 2019–2020, are presented. Early mounds were covered by a huge kurgan above another, later burial of adults. The entire complex was built by the Yamnaya people at the turn of the early and middle stages of this culture, about 3300–3100 cal BC. Remains of three children, aged about 6, from two graves, were examined. Severe pathological conditions were discovered. The child from burial 3 died of metastatic cancer. Child 1 from burial 4, represented only by a cranium, possibly suffered from scurvy. The oncological condition may have been triggered by a long stay at a smoky hearth or proximity to a metalworking site, since the Yamnaya population of the Southern Urals was engaged in an intense exploitation of copper deposits. In both children’s burials, common elements of the Yamnaya funerary rite were accompanied by certain unusual features. Vessels were similar in form and decoration, but different in manufacturing technique. The organic substances of which the mats under the skeletons were made display certain differences. These features suggest that children belonged to related but separate groups. Children buried under early mounds apparently had a special inherited social status that had an effect on the further construction of the kurgan for members of the elite.