The best discussion is in a number of posts on John Hawks' blog:
Neandertals Live! ⚠️ ↗
African population structure and Neandertal population mixture ⚠️ ↗ (a reply to Dienekes Pontikos' dissenting view ⚠️ ↗)
Libidinous Neandertal men and the women who loved them ⚠️ ↗
The Neandertal fraction ⚠️ ↗
See also Razib Khan's ⛓️💥[Removed].
This would explain, anyway, why this research found no trace of Neanderthal mitochondrial DNA, which is passed down only by mothers.
There is no trace of Neandertal Y chromosomes either. As John Hawks points out, the reason is probably very simple and basic: natural selection.And the correct spelling is Neandertal; Neanderthal is more than a century out of date.
Surf safe;)
NFiH