Hi there ! Even silky coats can have a curl from what I've seen, Cheri does and I use my hair dryer to straighten it sometimes but mostly I let it be. It's not like she's needs to impress anyone
The rest of her hair hangs very straight
I think lots of us have little silky coated yorkies that have that 'curl on the butt'.
Edited to add - this does not mean they're mixed !