The producers from A:R (Which can hardly be regarded as canon) showed that the host's DNA does have a substantial effect upon the Alien's DNA. Even though the queen was cloned, and some of the genes got mixed up, it still developed a womb, which is twice as human as Ripley 8 is alien. This shows that alien DNA has a large number of gaps with which it can incorporate the host's genes. Inside the host's body, there must be, at a point, some sort of connection to the DNA helix, because how else would the Alien acquire characteristics from its host? If the predator reproduction method is with the mouth, the embryo's 'brain' maybe subconsciously copied the genes for that, knowing that when it became an adult, it would help to build a colony, because, possibly, the pred-burster felt the queen's presence disappear in AVP. I mean, It was right there in Scar when the Queen went down. And possibly knowing that it was the only one left, it made those alterations in its genes. I'm just saying that the reproduction method, scientifically, may not be as farfetched as some of the stuff we've seen so far.
