Background: The development of gross motor coordination (GMC) is governed by biological and environmental factors whose effect sizes are still unclear. Aim: To investigate sibling resemblance in GMC, as well as biological and environmental correlates of GMC among Peruvian children. Materials and methods: The sample comprised 1256 biological siblings (6–15 years old), from three geographical areas of Peru. GMC was assessed using the Korperkoordinationtest für Kinder (KTK) test battery. Anthropometry, biological maturation and physical fitness (PF) were also measured. Multilevel modelling was performed using Stata 14 software. Results: In general, sister–sister pairs (SS) showed the highest resemblance in GMC (ρ= 0.24) compared to brother–sister (BS) (ρ= 0.10) and brother–brother (BB) pairs (ρ= 0.07). On average, BB pairs had higher GMC than SS pairs and older siblings had higher GMC than younger siblings. Further, those with lower body mass index (BMI) and higher PF had higher GMC. There was also a significant interaction between age and PF with GMC. Siblings from the rainforest region demonstrated higher GMC than those from sea level and high-altitude siblings demonstrated lower GMC than their sea-level peers. Conclusion: These results demonstrate statistically significant sibling resemblance in GMC. Age, BMI, PF and geographical area were significant correlates of GMC.