From which ethnic group do most Canadians originate?

There is no one dominate ethnic group in Canada.

The majority in many areas are first (immigrants) and second generation Canadian primarily from Asia, Indian, China and other.

The largest hyphenated Canadians would be French-Canadian's at about 25%.

Many Canadians are ethnically Canadian (about 20 to 30% do not hyphenate their Canadianism). Many of them originate from Canada and proudly so. Ethnic Canadians have faced jail for claiming to be ethnically Canadian on Canadian census. After a few hundred years they have no connection to any other land, other than historically in which case we are all African mostly via Europe and Asia.