What causes gynecomastia?

[combatwombat]

Is it in your genes? or is it something that is influenced by lifestyle? I have gynecomastia at the age of 18 and i've had it for about 4 years.  But my brother who is 16 has no trace of it.  Hes like the poster child of a gynecomastia free chest.  Did i do something to influence my gynecomastia? or was this just in the cards? i dont think its very fair that i have it and my brother doesnt....
And at 18 can i take some pills or something to manage my hormones and perhaps decrease the gynecomastia a bit?

[Paa_Paw]

There are lists as long as your arm of things that might cause Gynecomastia.

The truth is that the term used to describe the cause of most Gynecomastia is: "Idiopathic."

"Idiopathic is a medical term that in common English means either: "Your guess is as good as mine" or possibly "I dunno."