Being Photographed is a skill based activity, and is all about the correct technique.
The average person has never been taught these techniques and that is why they always look ordinary in their photos or they just avoid being photographed all together.
Like most things, if you understand the best techniques you will do them better! ie driving, riding a bike, playing golf, cooking, building etc etc.
Being Photographed is no different! Head position, eye position, mouth position these are all things that can be taught.
Don't be tricked into using a Headshot that your friends and family like. Lets be honest, your friends and family would like any shot you do, they are your friends and family !
Your Headshot is actually about people looking at you for the first time because they are looking for someone that does what you do for a job.
The question you should be asking about your Headshot is not "Does it show my personality" but "Does it make me look like I am really good at my job"