My dad is bald. It used to be by choice but now, its um... doesn't grow back?
The term of what he is going through is called MPHL male patter hair loss
Uh oh that sounds like its not ever coming back!
It may or may not come back.  In males the hair loss often presents a receding hairline 
I see. Are there treatments for it?
I have found one treatment its called minoxidil, or a hair transplant surgery are the most benefiting treatments