The data suggests that Republican Rome was a mix of the local Copper Age populations of central Italy and incoming Bronze Age nomadic populations from the Pontic-Caspian Steppe. This doesn't map neatly to any modern population, but is fairly generically "Iron Age European."
The Imperial Era was more cosmopolitan, with massive genetic inflow from the east Med:
> During the Imperial period (n = 48 individuals), the most prominent trend is an ancestry shift toward the eastern Mediterranean and with very few individuals of primarily western European ancestry (Fig. 3C). The distribution of Imperial Romans in PCA largely overlaps with modern Mediterranean and Near Eastern populations, such as Greek, Maltese, Cypriot, and Syrian (Figs. 2A and 3C). This shift is accompanied by a further increase in the Neolithic Iranian component in ADMIXTURE (Fig. 2B) and is supported by f-statistics (tables S20 and S21): compared to Iron Age individuals, the Imperial population shares more alleles with early Bronze Age Jordanians (f4 statistics Z-score = 4.2) and shows significant introgression signals in admixture f3 for this population, as well as for Bronze Age Lebanese and Iron Age Iranians (Z-score < −3.4).
> https://www.science.org/doi/10.1126/science.aay6826
The data suggests that Republican Rome was a mix of the local Copper Age populations of central Italy and incoming Bronze Age nomadic populations from the Pontic-Caspian Steppe. This doesn't map neatly to any modern population, but is fairly generically "Iron Age European."
The Imperial Era was more cosmopolitan, with massive genetic inflow from the east Med:
> During the Imperial period (n = 48 individuals), the most prominent trend is an ancestry shift toward the eastern Mediterranean and with very few individuals of primarily western European ancestry (Fig. 3C). The distribution of Imperial Romans in PCA largely overlaps with modern Mediterranean and Near Eastern populations, such as Greek, Maltese, Cypriot, and Syrian (Figs. 2A and 3C). This shift is accompanied by a further increase in the Neolithic Iranian component in ADMIXTURE (Fig. 2B) and is supported by f-statistics (tables S20 and S21): compared to Iron Age individuals, the Imperial population shares more alleles with early Bronze Age Jordanians (f4 statistics Z-score = 4.2) and shows significant introgression signals in admixture f3 for this population, as well as for Bronze Age Lebanese and Iron Age Iranians (Z-score < −3.4).