I’m a 24 year old male, and I have a family history of balding. I have close-cropped hair, and I noticed that I can see a bit more scalp in the “runways” along the sides of my head and around the crown than I can see on the top of my head. The individual hairs in the thinner areas do not actually seem to be miniaturized compared to the hairs in the thicker areas, which is what confuses me. It looks like there are just fewer overall hair follicles in the thinner areas. It may have always looked like this and I never noticed, since I never thought to check until my brother started balding. My front hairline is not receding at all. Could this be a normal (non-balding) hair pattern, or is hair always completely uniform over the entire head on a non-balding person?
There are two independent measurements that will point to what is going on. There is the actual hair counts by area and miniaturization by area. Both of these metrics can be obtained when you map out your hair for miniaturization. I do not always do hair counts in all of the areas I map, but in your case, this might be worthwhile.
Genetic hair loss causes both miniaturization (thought to be a precursor of balding, but not always) and direct reduction of hair counts without going through the miniaturization process. What you are viewing should have numbers put to it so that the diagnosis is in hand answering the basic question: Do you have genetic balding going on?
Most people will have some variations of densities by the part of the scalp, and these differences do have some consistency in the population. Hair along the sides is often less dense than hair in the very back of the head, for example. Yesterday however, I met a man who had just the reverse — a higher density on the sides, less in the very back. Good baselines are critical to understanding your hair loss, and good measurements in the hands of a good doctor will reveal that information for you.