Absent Religious Moral Framework, (The Proposition On Offer)

I have a presentiment that this should prove to be a most interesting argument! Next, I would like to accept the definitions my opponent gave and confirm that I will ignore any religious objections. I also accept there would be no physical health implications if two unrelated siblings were to engage in recreational sex with each other. However, the couple may well find that they are shunned by society, who would no doubt regard their relationship as "wrong". For example, let's say a couple of sibling lovers still live at home and their father, Mr. Shagnasty, has invited his boss and his wife round for dinner: Mr. Shagnasty – Hello sir, hello Mrs. Bigbossman, please come in. May I introduce you to my wife, Nora, my son Barry and my daughter Kristy-Agnes? Mr. Bigbossman – How do you do everybody? This is my wife, Mrs. Bigbossman. Mr. Shagnasty – Do take a seat, sir, Mrs. Bigbossman. Kristy-Agnes, would you kindly get everybody a drink? Kristy-Agnes – That's not fair – I laid the table. Why don't you ask Barry to do it? Mr. Shagnasty – Just do it, young lady and any more arguments from you and you'll get no dessert. Kristy-Agnes – Okay, okay, but no booze for you, Barry, I don't want a repeat of last night – do you know what I mean Mr. Floppy? Nora – Thank you very much, Kristy-Agnes, I'm sure Mr. and Mrs. Bigbossman don't want to know what you and your brother get up to in bed…which reminds me, Barry, when you and your sister have finished having sex with each other, please be kind enough to put the condoms in the bin, I'm sick of having to pick them up off the floor… Mr. Shagnasty - I don't know, kids today eh, sir? Although I'm sure your son and daughter don't expect your wife to pick used blobs up off their bedroom floor after they've had sex together… Mr. Bigbossman – Eh? Er…well, funnily enough, Shagnasty, my children don't actually sleep with each other. I know you come from the countryside, but here in the city people tend to take a very dim view of incest, myself included. Mr. Shagnasty – No, no, sir, no, you don't understand, it's okay because they are both adopted, and there is nothing wrong with adoptive siblings engaging in recreational sex. Also, as the two individuals are not related, there's no danger of them giving birth to some mutant baby after they get married. Mr. Bigbossman – Nothing wrong? Married? What the. .. ? Shagnasty – Yes, there is nothing morally outrageous about adoptive siblings getting married. That's why I was hoping to get that promotion, sir – as the father of both the bride and the groom, this wedding is going to be a very expensive affair indeed. Mr. Bigbossman – Jesus Christ on a f***ing bike… Mrs. Bigbossman – Er, so Kristy-Agnes, how do you feel about changing your surname to your fiancï¿½e's when you get married? Kristy-Agnes – Well I'm happy to take his name but I'm a very liberated woman so I'm going to use my own name as well: I'll have a double-barrelled surname… Mr. Bigbossman – So you'll be Mrs. Kristy-Agnes Shagnasty-Shagnasty? Kristy-Agnes – Yes. Mr. Bigbossman – F***ing rats c*cks, you're all crazy! Sick and crazy! Come on Mrs. Bigbossman, we're leaving. And as far as your promotion to Chief Child Protection Officer is concerned, Shagnasty, you can forget it. You see, although adopted siblings having sex for fun is not, technically, incestuous and it may not be illegal for them to get married, normal social conventions dictate that these things are wrong and the wider community is likely to shun brother and sister lovers, even if they are not related by blood. Thank you.