help with genetics

[colorin]

One of my gouldian pairs are as follows:
Cock: red head, white chest and green body (black head ring. It's not a diluted)
Hen: red head, purple chest and green body

The gouldian genetic forecast program stated that from a pair like that all chicks would be Red head, purple chest and green bodies.
Now, 3 of the 4 chicks have just fledged and one of them is definitely lighter in colour (not yellow, which made me think that either the cock or the hen must be split for something.
Went back to the forecast program to try changing cock or hen body colour to find out... but it doesn't let me split the cock or the hen for yellow, only for blue.
(withouth changing the physical appearance of both birds)

I'm attaching a photo I did a few minutes ago (I'm afraid the lighter one is looking at the camera but still you can see that his back and head is not as dark as its siblings-

[Diane]

Is it possible that one of the other cocks is the father, or maybe another hen laid that particular egg? I guess the only way to really know is to wait for the youngsters to colour up.

[colorin]

I don't think the other cock is the father. But I guess I'll have to wait until they colour up. Today the 4th chick fledged and it has the same lighter green.So there are two darker green and two lighter. But it's green indeed,not charcoal.

[Alex]

Ive found if there is a runt in a litter they often dont get as brightly olive as juveniles as the others, althouhg friends tell me Im just looking too hard.

[gouldianpaul]

Hi Colorin,

Genetically all birds from this pair should all be normal split for White breast...I suspect the lighter colored bird will eventually color up to be normal as well...the only other possibility is that both parents were splite for the recessive dilute mutation and the lighter colored bird is recessive dilute...cheers, Paul

[Bgould]

I was thinking along the same line as you gouldianpaul then I stopped to think this further. I dont think that the recessive dilute is found outside of Australia but I could be wrong.

[colorin]

Well, the 4th chick fledged and it's also lighter in colour. It's definitely green colour (not charcoal) but not as dark as their siblings.
I guess I'll have to wait until the colour up, and it very well could be that they end up being the same colour..

[colorin]

I have just taken a photo. I'm sorry it's not very sharp, but you can see their backs (the one in the middle is one of the darker siblings)

[Diane]

Yes its definitely lighter, will be interesting to see this one colour up to see what it finally looks like.
Good looking young.

[KENTUCKY]

Hi Colorin,
There are two things you can do, either try to be patient and let nature take its course, or plug a few head, chest, wing and body feathers and within six weeks adult feathers will have replaced those you have removed earlier from the bird, it will reveal anything unusual. Good luck Ralph P.S. I strongly suspect that it is a lighter coloured youngster that will molt out to be a Normal. Keep us informed.