If you mean the tapering of individual strands, I think that mostly comes from manual manipulation. I think it's a result of the cuticle gradually chipping more from the ends, dramatically enough that you can see the strand is thinner on the bottom. It could also be from not using products that strengthen/fortify the strands (like coconut oil).
If you mean "tapering" as a group of hairs, like thinner ends, I think that's mostly from breakage, possibly midshaft. Less likely, it's from groups of hair in lower areas growing faster than sections above (giving a natural, but dramatic, layered or "tapered" effect).
Could you clarify what you mean by tapered?
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