Fluffy tail, different than the others... genetics?

[CabritaChicks]

I am coming here to ask a question that has been looming over me. Apologies for posting a few threads in a day.
I’ll admit—I’m new to chicken breeds and genetics. Right now, I have three Rhode Island Reds, all about 6ish weeks old.

Since the very beginning, one of them—Isla—has stood out. Her tail is noticeably fluffier and rounder, while the others have those classic, sleek, triangular tails. She just doesn’t quite match them in shape.
I’m wondering:

• Could this difference in tail fluff and shape be genetic?
• If so, does it possibly mean she’s not a purebred Rhode Island Red?
• Or is this just normal variation within the breed?

I’m not concerned either way—I love her regardless (in fact- she is my favorite and also the ring leader)—but I can’t help being curious. It’s been bugging me just enough to finally ask. First two images are Isla. The other images are the other two (Indigo and Iris). Last photo is side by side.

Thanks!

 

[BlindLemonChicken]

I think it’s just the way it looks because it’s growing in. I’m not an RIR person but usually that gangly teenage chicken phase is a feathery mess and some baby fluff is still hiding under big girl feathers. I see a little downy fluff still around her face. I bet in a couple weeks she will look just like the other girls. That being said, I have seen variation between chicks of the same breed from the same hatchery. Two Delawares I had a few years ago were so different I was convinced one was a cockerel until it laid an egg. Same age, same hatchery, but Click had much thicker legs than Clack in addition to penciling in the neck feathers. I think her comb was bigger too but the legs really had me confused.