"While the term 'impregnation' and 'implantation' are liberally used to describe this process, they are not strictly accurate; studies by Lasalle Bionational have shown that no actual embryo is inserted into the host. Instead, the infant Xenomorph begins its life as a knot of specifically tailored cancers that bring about chemogenetic restructuring of the host's cells, essentially "building" the chestburster from the host's own biological material at a cellular level."
So the Facehugger deposits a tumor into a person's esophagus, which then co-opts its host's cells, and grows into the xenomorph. That they knew this all the way back in 1993 just adds validation that the Alien vs. Predator movies were indeed terrible and should in no way be considered canon. Also, for decades there has been this idea behind the original Alien that it was in fact some biological weapon created from material that could co-opt genetic material from a living host. In other words, it wasn't just something that Ridley Scott pulled out of his ass to make Prometheus.
I'm looking forward to seeing the movie tonight, and I can't wait to review it on Monday. In the meantime, if you are out and about and see an alien penis snake and are a scientist, it still wouldn't be advisable to reach out and pet it.