Ancient aliens and genetics

[ChrisIB]

Does the interbreeding and genetic manipulation suggested by ancient alien theorists have testability?
Take the Nibiru myth

The Annunaki arrived and began extracting gold from sea water. Unable to get the yield, they instead turned to mining.
To provide the workforce a hybrid Annunaki Hominia was genetically engineered. Later a variant which could breed was produced.

I have recently read 'The seven daughters of Eve' by Bryan Sykes, a world authority on DNA. He details the story of how using mitochondrial DNA, which only goes down the mothers line and does not change, it was possible to trace all European ancestry to seven women.
Would such traceability negate the Nibiru and other such claims?