Another surprize blue

[CandoAviary]

I found this little fellow in the aviary...he and 3 siblings were pushed out of the nest, The littliest one died. Dad pushed them out and I see why....they have laid new eggs. The blue and other one look a little thin. I will catch them up if they are not being fed. The one on the right is flying well and eating seed and millet.
In the Pine Tree Aviary I had 4 pair of RH PB GB. The males were bred by me last year as were 2 of the females. They were all from RH PB GB parents or one parent out of the 8 was have been a BH (hen). As far as I knew none were /blue and none threw any blues last year.
The 2 other females I bought were from breeders who said they were normal GB.... well I guess there are some /blue in this bunch.
Who I believe are the parents are (colony breeeding so ?) father RH PB GB, his parents were both RH PB GB and grandparents on the cock's side RH PB GB. The hen's side is all RH PB GB on both sides, grandparents also RH PB GB.
Strange that there would be a blue out of this line of birds that for at least 2 generations never has thrown one..... obviously they were passing a /blue gene or...possibly... it brings me to this question.

How did the first mutation happen? Obviously there wasn't a /blue gene yet. I know that somehow the color gene mutated and the yellow/luetin was lost so the bird appears blue but could this still happen today? A mutation happening on it's own? Or would you just suspect a /blue gene that has just now shown up?

[nixity]

But since you are colony breeding you really don't know who the hen bred with or who the blue came from, really..
It's more likely that the birds are carrying blue - perhaps one of the new hens was carrying it unbeknownst to the owners, and your line carries it too, but since you were only ever breeding them with normals, it never showed itself.

[CandoAviary]

Thanks Tiffany,
that is what I figured that there must be at least 2 /blue in there that happen to hook up.
The ones taking care of the chicks are the ones I call the parents...though I know it could be any one. I will pair the 2 together in a cage to see if they are the ones for sure. I hate colony breeding. I thought I would do the red head thing, 4 pairs to track the male/female ratios for the year. But they have tossed, abandoned , killed, are attacked older siblings...... In my opinion, there would be no chicks if I had not removed some. The ones that died I will never know what there sex was so...so much for those records
I have one more clutch to fledge and that's it for colony breeding gouldians
I am finding in my cage breeding so far the same head colors and the mixed head colors are throwing 60% males and 40% females. It's just that I sell more females than males