1. Does it really?The answer is, yes it can. Some studies have shown that hair at the back of the head tends to grow faster than the front of the head (Eur J Dermatol, pp 28–32, 2004). We are talking growth rate here. The experiment involved cutting the hair and then measuring its length after one month.
2. How big is the difference?
The difference was not really that much approximately quarter of an inch over the year.
3. So why the difference?It actually seems to boil down to thickness of the hair strands (remember this is the reason why men's hair grows faster than women's).
4. A quarter of an inch is not much, what about several inches difference?I have not seen a study showing this but this does not mean it is not possible naturally. I do think though that texture differences and handling are probably more likely to contribute to this effect. Many of us have noticed that our hair may look or behave differently on different parts of our head.....for example I have a smoother curl at the back of my head compared to the rest of my head which is most definitely not interested in forming spirals.
I think that when the difference in hair length begins to go into several inches, perhaps the focus should not be growth rate but rather retention of growth. The tighter the curl, the kinkier the hair, the more gently you need to treat it so it can keep up with the rest of the hair on your head.