My theory on other peoples' private sex lives is this: if you don't like it, don't do it - but don't tell me what I can and cannot with my own body in consensual adult relationships. This includes heterosexuality, homosexuality, bisexuality, menage a trois (or more, should you all so decide), etc. Note that the key words in my initial statement are consensual and adult - thereby eliminating all forms of forced sexual relationships, and any type of sexual relationship with children.
There are quite a few sexual practices out there that I choose not to engage in - but that doesn't mean that others cannot choose them for themselves. Also notice the word private - what other people choose to do, again, consensually among adults in private is no one's business but their own.