Ancestry of East England?

Is Essex mainly of Viking and Saxon ancestry? I've read that multiple Celtic tribes lived there before, during and after roman occupation. Even when the Saxons invaded they crossbred with the Celts. I've even read about Viking and Saxons being a minority not just in East England but the British Isles itself. I'm always finding different information that we don't descent from Celtic, Viking or Saxons but from Basques and other Cro Magnon people that came to the British Isles some 20,000 years ago. It's very confusing because there is a lot of different discoveries about this and everything gets all messy. I always considered myself of Saxon and Viking descent because that's what I've read in my family documents and that's who inhabited that region.