Late Romans mostly Celt?

[varistus]

In the U.S. we have a strong Irish American population(or part),to the tune of over 40 million. Many Irish-Americans consider themselves Celts and descendants of such. Feelings are very strong here and many feel the Romans did a grave injustice to Europe in attempting to eradicate their civilization.
I would not even attempt to tell them that the Romans really just absorbed them and Late Romans were mainly Celt and German. They would never buy that. Celt to them is Celt...an ethnic group and a spiritual identity. It is really strange but just the way it is here.