OK, I really shouldn't come back to this thread - as clearly I'm not mature enough but...
I was thinking about it while I was getting up this morning (do I have no life??) and why I got hot under the collar is because the OP's question wasn't 'would you object to your au pair having sex in your house?'. To debate that is all well and good - but this was about sexuality, not sex, and that's where prejudice starts to rear its ugly head.
Like the more than one occasion on this thread where being gay has been described as being a 'lifestyle choice'.