I think we decided that that statement was a bit of hyperbole. The Galatians were certainly present in enough numbers that specific phenotypes are still present in Egypt, which is a good indicator that enough was added to the gene pool that traits didn't simply disappear over time due to genetic drift. But "ethnic makeup" doesn't really work.

It get a little more complicated than that, but that is about a semester's worth of ecology, genetics, and population evolution boiled down into a paragraph. More to the point, however, that paragraph was written way early in EB's development. In the recent work we've done, I don't think you would see a description like that.