Nape texture is always different from the rest of my hair

When I comb my hair after towel drying it dries mostly straight, except the nape will be wavy.

I had thought this was either because my nape hair is actually wavier than the rest of my hair, and/or because it dries the slowest so it retains the most texture.

However, recently I've been trying a wavy styling routine (combing while very wet, then scrunching out excess water with a towel, sometimes a hold product) and getting good waves throughout the rest of my hair, but now the nape is straighter than the rest! Can anyone explain why that would happen?