"My great-aunt and great-uncle were siblings who had an incest relationship for most of their lives. They shared a house for the last decades of their lives which I always thought was very sweet, siblings caring for each other as they got older. Years ago, I was talking with my father about how much I missed them when he just offhandedly told me that the two were in an incest relationship since they were kids. My mother confirmed, laughing at me like I was dumb for not knowing when it was obvious, which it apparently was since everyone in the family knew except me."