Bell Beaker Folk

[sparkey]

but still it doesn't explain why also noth italians aren't the same as french (and northern italy was inhabitateds by celts too insubres, boi, carni, cenomani etc..)...

No, North Italians are quite close to the French genetically, see the first chart spongetaro posted here. Also see Maciamo's tables, where we see that North Italians are 55% R1b vs. 11.5% J2, close to French from Auvernge (52.5% vs. 8%) but not that close to South Italians (29% vs. 23.5%).

[julia90]

still they aren't the same population

[sparkey]

still they aren't the same population

They are close enough to postulate significant shared history, that's my point.

[Grizzly]

The problem is that when we speak about Italo-celtic expansion, a lot of people guess horses with Italic and Celtic knights spreading in Italy or anywhere else.
Indo-europeans were warriors invaders, no doubt, like Huns, Magyars or Mongols were so. But after these invasions, some areas has adopted their vocabulary, other not.
The italic language is the result of the "creole" of this indo-european language in Central Italy, the Celtic one the same result, but in the high-Danube regions sub-structure, the Germanic the result for the Scandinavian substructure etc...There are similarities between the first and the second, but also the second and the third. I don't know in which extend Italic should be closer to the Celts than the Germanics.
The regions who have not adopted their language for many reasons will appear to us as the Etrusques, the Iberians (maybe current Basques), the Ligurians...in fact, a lot of Southern peoples, because Indo-europeans came from the Eastern plains. That's why the Atlantic school is hardly believable.