Editing Openai/69186d20-2d14-8013-b9c6-c09000f173f6 (section)

==== These are exactly the “shared PIE retentions”: roots that show up in: ====
* Celtic (Irish/Welsh),
* Italic (Latin),
* Germanic (English/German),
* often also Greek, Indo-Iranian, etc.

They support “Celtic is Indo-European”, but they don’t by themselves tell you whether Celtic is closer to Italic or to Germanic, because everyone inherited them from PIE and then did their own sound changes.

The Italo-Celtic argument is built not on these, but on weirder shared innovations (superlatives, specific case endings, particular sound changes) that are not widespread across the family.

If you want, next step we can:
* pick a single PIE root you care about,
* trace it systematically through Proto-Celtic → Old Irish / Welsh vs Proto-Italic → Latin, and then Proto-Germanic → English/German, so you can see exactly how the different branches twist the same starting point.