Confessing My Stepbrother's Secret Desire

I've been in an open relationship with my partner for about a year now. We both agreed that we'd explore what makes each other happy and fulfilled without any jealousy or hard feelings. So when I found out my stepbrother had a particular interest... well, it wasn't exactly the kind of thing most people would talk about openly. My stepbrother is in his early twenties, just like me. We've always been close, but lately there's been this undercurrent between us that neither of us could really put our finger on. It started small, more innocent touches when we were alone together and these lingering looks that said so much more than words ever could. One night, after a particularly heated discussion about boundaries in open relationships, I decided to be completely honest with him. He seemed surprised at first but then confessed his own secret desire for me... as my stepbrother. It was strange, knowing there's something taboo and exciting about the idea of being related by marriage instead of blood. We agreed on some ground rules, no one else needs to know, respect each other's limits, and most importantly that we're both adults making a consensual choice here. We've been keeping it under wraps but sneaking moments together when we can. It's not about the physical side so much as this forbidden thrill of breaking those societal norms... I'm sharing this now because I feel like there's nothing wrong with exploring what works for us, as consenting adults in an open relationship. People might think differently, but I know myself and my partner well enough to know we're doing okay. There are a lot more important things to worry about than some made-up taboos.