What is the SHORTEST a person's hair will grow?

Different people’s hair has a different terminal length, that is, the length at which it stops growing and will eventually fall out. In other words, not everyone can grow their hair down to the same length. Some people can grow their hair extremely long (the current record holder would be a Xie Qiuping from China, whose hair was measured at 5.62 m (18 ft 5 in) on 8 May 2004); however, as most people don’t deliberately let their hair grow to its terminal length, we don’t know this statistic for most of us. I would make an educated guess that the average person’s hair can grow to anywhere between their chest and their knees, but don’t quote me on that.

But what about people whose hair won’t grow past an unusually short length? I have heard numerous anecdotal stories of people who claim their hair only grows to about shoulder length. I’ve even heard of someone whose hair is claimed to only grow to about collar length. Are there really people like that out there, and if so, can this be caused by genetics, I.E. can someone really have an inordinately short natural terminal length? Or would this always be caused by some kind of damage (environmental factors, breakage due to chemical processing such as perming or bleaching)? Any examples of someone you know whose hair grows unusually short?

To be clear, people whose hair won’t grow due to some blatant ailment don’t count. I have heard, for example, of people suffering from severe malnutrition whose hair had supposedly fallen out and was growing back as mere fuzz. These are obvious exceptions to the rule; I’m only interested in cases where a person’s terminal length is unusually short under “normal everyday” conditions (i.e. that it’s genetic, or at least due to chemical processing or other environmental damage).

When I was in junior high, we had a math teacher who wore her hair very short. It would have almost met the requirements for a man’s hair in the military. I assumed she did so by choice, but I once overheard her talking with another teacher, saying it was several years’ growth.

You don’t need to look very far for an example.
Body hair length is typically much less than head hair because the growth (anagen) phase of the body hair follicles is measured in weeks rather than the years for head hair. The difference is considered to be under genetic control.

In the reverse situation the body “hair” of sheep (ie wool, there is a structural difference) goes continually while the facial hair of sheep is short and regularly shed.

There would be every reason to expect that at least some human has/had a genetic make up which doesn’t make that distinction and their head hair grows/grew in the weekly cycles as it does in other mammals and animals

Stereocilia never seem to get too long.

You do realize my question pertained to scalp hair only?

My hair only goes does to about an inch or two below my shoulders and is all scraggly and split ends for those last few inches.

So much for that long hair I was going to grow out as an adult.