Short answers, pulled from the story.
The word Italic refers to a specific subgroup of Indo-European languages spoken by the Osco-Umbrians and Latino-Faliscans. This strict linguistic definition excludes non-Indo-European groups like the Rhaetians, Ligures, and Etruscans from the core group.
An migration across the Alps from East-Central Europe occurred around 1800 BC according to Barfield. Massive migrations of Proto-Indo-Europeans moved from the Yamnaya culture into the Danube Valley between 3100 and 3000 BC before tribes brought Beaker culture to the Po Valley and Tuscany by the late third millennium BC.
In Tuscany and part of Emilia-Romagna, Latium, and Campania, this culture evolved into the Villanovan culture by circa 900 BC. The Latial culture emerged south of the Tiber while the Este culture appeared in the north-eastern peninsula.
After Roman victory secured, all peoples in Italy except Celts of the Po Valley received Roman citizenship following the Social War in the early first century BC. Subsequent centuries saw Italic tribes assimilated into Latin culture through a process known as Romanization.
A genetic study published in Science in November 2019 examined remains of six Latin males buried near Rome between 900 BC and 200 BC. These individuals carried paternal haplogroups R-M269, R-311, R-PF7589 and R-P312 alongside maternal haplogroups H1aj1a, T2c1f, H2a, U4a1a, H11a and H10 with about 25 to 35 percent steppe ancestry.