We have always tried to be discreet but our son figured it out when he was 18 and our daughter when she was 16. My wife has sex with the husbands of some of our couples-friends, so those guys know of course, but their wives do not know. My wife's brother and his wife know. My brother knows. I have shown my brother nude pics of Kate and pics of her sucking and fucking other guys. He loves it.
My five male cousins know. We had a pool party with just the guys. It turned into a skinny-dipping party, so they all got to see Kate naked. My youngest cousin was spending the night because he loved in another city. He got to fuck Kate after the party and he told the other cousins that he fucked her while I watched. Family gatherings are hotter now that the guys have all seen my wife naked and know that our cousin got to fuck her.