Andy,
First of all, Bald is really Beautiful.
My (late) best friend was a very sweet bald old uncle, who was blessed with a curly ponytail towards the back! (Andy do you also have a ponytail that is not visible in the picture??? lol)
I also suffered with hair thinning over many years. The possible causes according to me-
I get scalp folliculitis frequently, using a medicated shampoo for it, lessens the hair loss. it may have something to do with lowered immunity and anemia.
I have an oily scalp that causes hair loss - i attribute it to my hypothyroidism. before I was first diagnosed, my hair fell out in bunches.
I also get tiny bald patches on and off in the front, I am told it is an autoimmune issue?
People take hormones etc to grow hair - but it is NOT advisable if you ask me.
I wonder sometimes if evolution will eventually make everyone bald?? :-) I mean is it really useful? My hair actually makes me feel much warmer than it actually is. Gives me headaches when i tie it up high.
I think people with scanty hair to begin with - notice hairfall more severely than the others who have thick hair.
Evening primrose oil caps help some people with thyroid related hairfall - but there's no proof to it. It helps eczema too - perhaps it rids the scalp of skin-problems related hair loss.
Biotin is another hair vitamin - but i've not seen results.