Golds are recessive. Lets call them g
Greens are dominant. Let's call them G (for now)
This leads to that triple helix gene thing..Ie. THREE strands of DNA.
Obviously, this is a gender related color gene, much like calico cats in nature.
You have females who carry either g or G genes.
You would have
|Green||GGG||(Not possible, as the gold cannot give a G for this.)|
|Green||GGg||(Possible is brown-gold matings)|
|Green||Ggg||(Most common in Bronze-Gold matings)|
Now this makes it look like a green could produce a gold if bred, but if G
carries a lethal gene, this prevents them from reproducing when combined with
others carrying that lethal gene. From what I gather, the Ggg can lay eggs
but they are always duds and infertile. The G inhibiting the ability of the
egg to fertilize.
Since greens outnumber all other colors combined, it stands to reason that
the males carry the genes on the X chromosome. All males (At least on Earth)
carry one X. If the color gene is tied to the gender, then perhaps it would be
mapped like this.
|Bronze||bgG||(As the color gene is attached to the gender, b is a recessive.
Otherwise there would be less greens..)
This shows Bronze carrying the ability to sire all colors, depending on how
the chromosomes remix. The egg either keeping two strands and only swapping
one or keeping one and swapping two, either way it works out, as only one Y
chromosome is possibly swapped, though in Ruth's case, he may be a weird case
where he has four chromosomes, like a male calico cat is a XXY (normal male
cat would be XY) due to one strand failing to split off like it was supposed
to. Male calico cats are sterile though.
This would make Ruth a XXXY, as an extra Y gene would have made him larger and not small and light built as he was.
|Ruth||bGG||XXXY||Color effected from extra X gene, producing white in this case.|
This allows Bronzes to sire all colors when combined with a golds genes, but browns cannot sire golds as they lack the recessive g gene. A blue could only sire blues and greens though, unless b is an incomplete res gene, so that it only works with other genes present.
|Bronze||bgG||XXY||The b carried on the Y gene.|
|Brown||bGG||XXY||The lack of g making it a brown, as browns can't sire gold.|
|Blue||bGG||XYX||The X chomosome reacting with the Y due to another gene(s) (N/n).|
Let call the other gene N or n....
|Bronze||bgG||YXX||Nnn||or any combo, as the N/n doesn't trigger in the presense
of a g (gold) gene.
|Brown||bGG||YXX||NNN||or nnn (More rare then a mixxing of N and n.)|
|Blue||bGG||XYX||Nnn|| (Mixing N's causing the reaction between the gender
chromosomes with no g present, producing blue.)
Working this out has given me a headache, but as long as it works, it helps explain how greens can be genetically sterile. F'lar simply thought that firestone was the culprit, since noone had ever seen a fertile egg from a green and it was 2500 turns from the time they were engineered, noone knew by F'lar's time that greens had been genetically engineered, much less the reason why greens were sterile. Note that F'lar thought dragons were 'bred' up from firelizards over time, not created in a lab in a few months.