Jar writes:
Immorality is also totally irrelevant except between the individual and that individuals God. Quite frankly, immorality is nobody's business other than the individual.
It depends on the context. The Captain of the Airship Hindenburg may say that whether or not anyone smokes in the privacy of their cabins is very much his business since the results could affect the whole ship.
I don't see where sex between two consenting adults would affect society,but others may say that there needs to be standards or else everyone could bring down the overall standard.
Murder is different. Anytime there is a murder, the perpetrator most definitely can and does potentially affect society.
You hit the nail on the head when you asked "whose business" a particular action may be.
Consider:
At Columbine High School, Dylan Klebold and Eric Harris personal lives and behaviors were said to be the business of their parents and authorities who should have seen it coming and attempted to stop them.
At whatever point society attempts to impose standards on others, we need to ask ourselves if the reason is that it is everyones business or not.