Studies evaluating DNA preservation in non-adults, or comparing preservation in adults and non-adults, are very rare. This study compares the preservation of DNA in the skeletal remains of adults and non-adults. It compares the quality and quantity of DNA recovered from different skeletal elements of adults and non-adults, and from non-adults of different age classes. In addition, the preservation of DNA in males and females is compared. Bone DNA preservation was estimated by measuring nuclear DNA concentration and its degradation, and through STR typing success. The study analyzed 29 adult skeletons and 23 non-adult skeletons from the Ljubljana–Polje archeological site, dating from the seventeenth to nineteenth century, and up to four skeletal elements (petrous bone, femur, calcaneus, and talus) were included. After full demineralization extraction, the PowerQuant System and the PowerPlex ESI 17 Fast System (Promega) were used for qPCR and STR typing, respectively. The results showed that, among the four bone types analyzed, only the petrous bone proved to be a suitable source of DNA for STR typing of non-adult skeletal remains, and DNA yield is even higher than in the adult petrous bone, which can be attributed to the higher DNA degradation observed in the adult petrous bone. In adult skeletons, petrous bones and tali produced high STR amplification success and low DNA yield was observed in adult femurs. The results of this study are applicable for the sampling strategy in routine forensic genetics cases for solving identification cases, including badly preserved non-adult and also adult skeletons. Highlights • Comparison between adult and non-adult skeletons is poorly researched. • Petrous bones, tali, calcanei, and femurs were analyzed. • Petrous bones produced higher DNA yield in non-adult than adult skeletons. • DNA degradation was higher in adult than non-adult petrous bones. • Petrous bones are the most suitable skeletal element for sampling aged non-adult skeletons. • In adult skeletons alongside the petrous bone the talus also produced high-quality STR profiles.