What were you expecting? There is no such thing as a genetic standard for what a "French" person is. They are mutts like most of us are. Just "old" mutts. My grandparents were from southern France and have roots from Spain and other parts of Europe. There were several distinct cultures there at the time they were born and raised there - the Basque being one of them.
My grandparents hardly even spoke the French language. Catalan was their main dialect.
As I understand it - Ancestry is developing a large DNA database and comparing DNA to family history reports and that's how they are using inductive reasoning to come up with these ethnicity projections.
So what exactly did your report say?