Genetic and DNA Speculation
That a Nephilim inheritance would be detectable in the genome — or that modern genetic engineering could reproduce it.
The claim
Two branches. Retrospective: a hybrid signature exists in human DNA and either has not been looked for or has been suppressed. Prospective: modern gene editing could deliberately recreate what Genesis 6 describes, tying the thread to 'days of Noah' expectations.
What genetics actually shows
Human genomes do contain archaic introgression — Neanderthal and Denisovan ancestry — which is documented, published and non-controversial. It is evidence of interbreeding between human populations, and is not evidence of non-human or angelic ancestry.
What would confirm it
A sequence with no plausible ancestral source, replicated across independent laboratories. Nothing of the kind has been reported.
Status
SPECULATIVE. Note carefully: the existence of archaic ancestry is often quoted as if it supported the theory. It does not.