Interestingly (just investigated as I did not know) Hair, fur and wool are all hair. It is just convention that humans call theirs hair and animal fur etc. the length that hair/fur grows to is. genetic. Whilst our head hair appears to grow unrestrained, it does have a finite length controlled by our genes which is why hair in other areas only grows to a shorter length. It is the density of the hair follicles that determine density.
No help whatsoever with the question, but I was curious.
We need some answers to our questions before we can continue.
am sure you will get the answer now.