gynecomastia runs in my family, but I was always the 1 with the severest case. at the age of 40, I had liposuction, and am doing ok 20 years later.
as a kid and teen i was bullied by everyone: school bullies, friends, family, even by my family doctor who squeezed them and blamed me for being overweight and causing this myself. more than once a bully would squeeze my boob hard---I have NEVER before or since been so humiliated and shamed, I hoped I would pass out. I cried for days, telling no one why, afraid to keep the story alive. I begged God that I would accept anything as relief--I would have gladly traded in my brains for relief.
when I started dating and sex, I was happy to see that at least SOME girls were not grossed out. to make matters WORSE, my gynecomastia was even worse with clothing, especially suits.
My advice: parents, never under-estimate how much your boy is suffering. get him to open up to u in private. then help him as much as if he had a severe illness. the shame and sadness is like no other. I never told my parents when kids called me 1/2 man, 1/2 woman. Do not let him bear the pain alone, but be discrete about it. do not force him to talk about what is, by far, the greatest pain of his life.