I tend to think that the way it works is not uniform. It will vary a lot depending on the species.
Putting an actual scientific prediction on it sounds impossible, as we are trying to understand alien DNA. For all we know the “Blue Print Particles” in their body’s are not even technically DNA.
That is how ALIEN they could be to us, so this would be very hard to predict in future generations of Aliens.
They may have environmental changes as well. Color of their background environment may alter their appearance like a chameleon. Look at the environments in the different movies.
A1: Lots of dark mechanical places, blackish grey alien.
A2: similar to the mechanical looking environment of A1, similar color scheme.
A3: Brown color all over, brown Alien,
A4: Mutation, but they did seem to reflect the iron color backgrounds a lot too, brown again. Keep in mind these ones were contaminated with too much human DNA.
AVP: dark Bluish pyramid, Dark Black, with slight tint of blue aliens.
OR this change may be totally due to something else, moisture levels etc...
We just do not know.
Now if lets say there was a world of Giants, with a facehugger susceptible organ, it would be logical that the adult aliens here would be equally gigantic. Probably even bigger than their host. It would make sense that they try to keep a size advantage over whatever their host species is.
This is one of the reasons why I consider the theatrical version of A3 to be cannon. If the aliens failed to pick up the trait of giant size on a world of Giants, than they are going to turn into smoldering piles of squishy acidic plop.
Some of the EU, such as AVP extinction says that only the regular adults can pick up host traits, but Queens are pure DNA. This is not cannon and just an assumption.
Now Going by the way the Queen looks and her function, I think that is reasonably safe to assume, or at least she mimics FAR LESS traits from her host. . The one in AVP was just fully grown, that is why she looked a little different, was more sturdy and bigger. To be conservative I am going to assume her host was human.
I for one assume the Queen’s DNA (if that is even what it is), is about 99.9% pure, and that her overall size may still be affected by host type, but nothing more, and she would always pass on the full 99.9% of pure alien DNA to next generation Queens, which would still keep the purity. The reason to have her size be affected by host type is so that she keeps her relative size advantage as compared to any species world that she may be forced to fight for her life on. Even on a world of Giants.
This is the whole reason why even having a mild bit of DNA assimilation. To be able to survive on the world of, and hunt for your host species.
Could it be that there is no such thing as a full strand of alien DNA, except what is in the facehuggers? Maybe without any host DNA at all that is what the alien is.
So 80% of the what an adult alien is, and 99.9% of what a Queen is, are the only predetermined parts, and that is the DNA that is passed on to further generations.
Successive generations would just fill in those 20% and .1% gaps respectively, with whatever their host species DNA was, and so on.
This way there is always a consistent look to the aliens, no watering down of DNA etc...
Or maybe there are no DNA gaps at all? Maybe they all have pure DNA, but the phenotype is affected by the host. The part of DNA that is passed on would always be there, but it assembles itself into specific phenotype by mimicking the host DNA pattern.
In the end they are ALIENS, so we just don’t know. I kind of like the mystery of it, and would prefer no exact math is ever put forth as cannon.