One day after my grandparents 50th wedding anniversary, which my brother didn't really want to be at, I was walking upstairs. (The bathroom is right at the top of the stairs.) Anyway, so the door was cracked a tiny bit, and I saw my brother sitting on the toilet seat. At first I didn't think a thing about it, but then for some reason I decided to go back and just peek in. Sure enough he was in there stroking himself, back and forth, with his eyes closed. I couldn't believe my eyes because I never saw anyone else masturbate, let alone my brother who was very into the Catholic faith. Anyway, I opened the door the whole way just to make sure my eyes were telling the truth. He didn't notice me.
After seeing that I got an immediate hard on. I then went to my room took off my clothes as soon as possible, and spread my legs and masturbated. After ejaculation, I looked up and there was my other brother, and he said, 'I am really freaked out!'
Then he proceeded to tell me that he went to the bathroom right after me, and saw my older brother, then came to our room (we share a room) and saw me doing the same thing. Since he didn't know how to, I showed him. From there we have all been keeping it to ourselves and making sure we are truly doing it solo.