Heya there Jforestquail!
.
I'd guess it's not so much to do with her age as it is her genes ...the pair's genes together.
I guess I was overthinking it. I've seen a lot of theirs hatch out over the past year, and maybe it just took this long for one to show up.
Incompletely dominant means that it mostly overtakes the other genes, so a bird with one copy of the gene will look different than a bird with 2 copies. With the fawn (Italian) gene, 1 copy makes it italian patterned and 2 copies makes it manchurian. In silver, one copy makes it silver (dilutes blacks to silvers and grays) 2 copies makes a pure white bird that is often weaker and wonāt thrive. In extended brown (without roux), 2 copies is Tibetan, one copy is rosetta. The incompletely dominant genes are what give us so much diversity. If an Italian is crossed to a pharaoh, you get what people often called speckled Italian, which is just Italian with a lot of spots, if you cross that bird to one that has one copy of Italian and one copy of range (often a rougher variegated pattern with indistinct spots blending into stripes), and you cross them, you can get the entire range of patterns offered by each one. You can get rosetta, speckled Italian, manchurian, and any other mix in between.
If you cross silver to silver, you have a 25% chance of a double silver (white) chick. Often these manifest as just eggs that donāt thrive, so you never knew you had doubles. But as your group ages and grow, is very possible that natural selection has weeded out some of the issues, and more are surviving. I started breeding my double silvers to purposely raise healthy ones because I want a group for meat, (theyāre noticeably white meat).I guess I was overthinking it. I've seen a lot of theirs hatch out over the past year, and maybe it just took this long for one to show up.
