On my head. Not all of my head mind you - only certain parts of my head. The crown, of course, but also a sort of semicircular region towards the front: both of these areas are very thin now....
I mean, honestly, there must be thousands of hairs on my head: what is the probability that these specific hairs just randomly stopped growing? If the value of the gravitational constant, the speed of light, or the charge of an electron were different by a factor of 10^-226, I would not have gone bald (Farley, 1977). It's absurd to think that this happened by chance. Clearly, someone has finely tuned the universe in such a way as to make me go bald.
So, yeah, cheers for that.