Westley, sadly short of breeding, there is no way to find out what is going on with this lot, and the best I can do is speculate for now (which helps in working towards a goal, especially so that you know what should happen if it is a morph, and how to expect it to express itself when breeding does occur). I had originally taken the light pair, as they were quite different to the rest of the littermates. Sadly, a lot of the characteristics of boas (patterns and colors) are polygenic traits (that can be passed from either parent to varying degrees, or even a combination of both parents), and not necessarily genetically reproducible as morphs (single gene morphs), unless you line breed them for the specific traits that you are going for. Again, as with ball pythons, normals can be so varied in their colors and patterns, that every Tom, Dick, and Harry seems to see some form of morph in their boa (I am one of those poor shmo's who sees microscopic differences and immediately gets excited for nothing seeing as I have yet to produce a new morph from my picks). Our boas in SA are also so mixed between BCC and BCI (back in the day, people just bred boas to boas) that I doubt there are many pure lines in SA, unless imported as such and kept pure in breeding.
The weird thing is that while the others get darker to an extent, these light ones just stay light, there is a definite difference to the colors (side and top), the saddle connectors are way too thick and have a really unique color, and let's not forget what the heck is going on with the head spears! That was another reason I chose the ones that I did. None of them have the characteristic needle-like head spear. These are all either crosses, broken all over the place, or have massive holes in them, which is not normal. The speckling that is occurring on them as well is rather interesting. When they were small, they looked peppered, but now, they seem to have cleaned up, and even in the patterns of the light ones, there is very little back actually showing through, as if something is trying to mask the black out, but not doing a good job of it.
As for the light pair... I don't know... Their mother was a different color to the other female that was covered by the same male, so it might just be that the light mother's genetics were stronger than the male's, and the offspring just took more like their mother. I haven't seen any other offspring since I got mine, so I cannot say how any of the other babies look. The two mothers and the father of these babies are also rescues, so their genetics stop right there as far as any lineage of any sorts goes. But, I have bought normal corns and bred out amel, anery, and motley from those normals, so nothing is impossible. The Arabesque, Aztec, Keltic and a few other boa moprhs were from "pet-shop snakes", so there is hope out there yet for me (or anyone else with the time, patience and eye for the subtle differences) to have a slim chance at discovering a new morph.
On that note, I have been speaking to some breeders who suggest this could be Keltic, or a similar gene type doing this. Sadly, I have to produce a striped super keltic in order to prove it as such, or a similar gene, and that is still a few years away. Unless I can find a female that is ready to breed, and use one of the males on her when the males are a little bit bigger (18+ months).