# If your sibling was obliviously in love with another sibling, would you tell her **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 18, 2014, 12:18am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115 "2014-01-18T00:18:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![monstro](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@monstro](https://boards.straightdope.com/u/monstro)\ **Post date:** [January 18, 2014, 12:18am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/1 "2014-01-18T00:18:18Z")
I just saw a movie that involved this and it’s got my mind a-working. Let’s say you have a younger sister. She’s the “old maid” in the family–never talking about a love interest or bringing anyone over for dinner. Her spinsterhood is always the 800-lb gorilla in the room. There are even rumors that she’s a big ole lesbian. One day she reveals to you that she actually has a man. A man who just happens to be ya’lls first cousin. She assures you there are no worries about children because she got a hysterectomy. Plus, they don’t want to have kids anyway. They plan to elope any day now. She just can’t wait! You want to be happy, but you know something she doesn’t. Years ago, an aunt told you that her son–the cousin in question–is actually your half-brother due to some fatherly “stepping out”. Further snooping on your part confirmed that this is true. You haven’t told anyone what you know because you promised you wouldn’t. You’re plenty skeeved out by the idea of cousins being together, so siblings getting it on totally freaks you out. And yet you see how happy your sister is. You know that this revelation would wreck her chances for happiness. So. Do you tell the sister what you know or just keep your big horsey mouth shut? 🙂 ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [January 18, 2014, 12:26am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/2 "2014-01-18T00:26:16Z")
Good luck to them both. > [@](#): > > Any kind of love is fine. It’s your hate you have to watch. (Margaret Cho) ---
**Author:** ![Elemenopy](https://avatars.discourse-cdn.com/v4/letter/e/b5e925/32.png) [@Elemenopy](https://boards.straightdope.com/u/Elemenopy)\ **Post date:** [January 18, 2014, 12:55am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/3 "2014-01-18T00:55:58Z")
I’m pretty sure this is a plot twist in every V.C. Andrews novel. Well, my instinct would be to keep my mouth shut, but truthfully, I don’t know if I could be quiet for years and years. Also, I’m sure that other relatives would put in their two cents; I doubt the big secret would go unmentioned for long. But the concept of it as you describe doesn’t really bother me. ---
**Author:** ![j666](https://avatars.discourse-cdn.com/v4/letter/j/9de0a6/32.png) [@j666](https://boards.straightdope.com/u/j666)\ **Post date:** [January 18, 2014, 1:19am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/4 "2014-01-18T01:19:54Z")
Who says Mom wasn’t stepping out? (She was probably feeling unhappy and neglected during and after the affairs, and Dad probably wouldn’t have noticed, or maybe even been relieved …) (But there would be no rumors; the third time we introduced her to a nice girl, she would have caught on and told us she was straight.) ---
**Author:** ![Antinor01](https://avatars.discourse-cdn.com/v4/letter/a/ecae2f/32.png) [@Antinor01](https://boards.straightdope.com/u/Antinor01)\ **Post date:** [January 18, 2014, 1:35am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/5 "2014-01-18T01:35:06Z")
Yes I would tell them. I would want to know if it were me, which could happen since I’ve never met my birth father and probably have siblings I don’t know about. The other issue is that since the marriage is not legal, it could be annulled by the government (depending on jurisdiction) or they could run into other problems down the road. ---
**Author:** ![Arrendajo](https://avatars.discourse-cdn.com/v4/letter/a/e0b2c6/32.png) [@Arrendajo](https://boards.straightdope.com/u/Arrendajo)\ **Post date:** [January 18, 2014, 1:50am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/6 "2014-01-18T01:50:18Z")
I’d keep my mouth shut. She’s had a hysterectomy, so inbred children wouldn’t be a concern. If an 800 lb. gorilla finds true love, more power to her. ---
**Author:** ![RTFirefly](https://avatars.discourse-cdn.com/v4/letter/r/c77e96/32.png) [@RTFirefly](https://boards.straightdope.com/u/RTFirefly)\ **Post date:** [January 18, 2014, 3:09am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/7 "2014-01-18T03:09:37Z")
> [@Arrendajo](#): > > I’d keep my mouth shut. She’s had a hysterectomy, so inbred children wouldn’t be a concern. If an 800 lb. gorilla finds true love, more power to her. Seconded. ---
**Author:** ![grude](https://avatars.discourse-cdn.com/v4/letter/g/e47774/32.png) [@grude](https://boards.straightdope.com/u/grude)\ **Post date:** [January 18, 2014, 3:30am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/8 "2014-01-18T03:30:34Z")
WAIT! Am I reading the OP correctly that there is unintentional incest going on here? Not consensual adult incest, just two people unaware? In that case I would discreetly let both parties know what I had heard, I would not publically embarrass them, but would feel an obligation to let them know and they can do what they want. I would not publically reveal the info. Letting people engage in unintentional incest is creepy to me. ---
**Author:** ![thelurkinghorror](https://avatars.discourse-cdn.com/v4/letter/t/7c8e57/32.png) [@thelurkinghorror](https://boards.straightdope.com/u/thelurkinghorror)\ **Post date:** [January 18, 2014, 5:55am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/9 "2014-01-18T05:55:24Z")
Realistically, genetic deformities etc. are a very low concern with inbreeding, especially first cousins. Like if the chances of a given 1/10,000,000 deformity doubles, it’s still only 2/10,000,000. I don’t have any family in this state, but it is a criminal offense so they should knock it off. However, where family is likely to live, it is apparently legal (really, California? Gerbils are illegal but cousin sex isn’t?). I would like to let them know, but as with revealing an affair when you are a third party, little good comes of you being the messenger. [Wikipedia](http://en.wikipedia.org/wiki/Cousin_marriage_law_in_the_United_States_by_state) ---
**Author:** ![Domesticated\_Primate](https://avatars.discourse-cdn.com/v4/letter/d/b487fb/32.png) [@Domesticated\_Primate](https://boards.straightdope.com/u/Domesticated_Primate)\ **Post date:** [January 18, 2014, 6:18am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/10 "2014-01-18T06:18:10Z")
> [@Arrendajo](#): > > I’d keep my mouth shut. She’s had a hysterectomy, so inbred children wouldn’t be a concern. If an 800 lb. gorilla finds true love, more power to her. Agree. ---
**Author:** ![Boogly](https://avatars.discourse-cdn.com/v4/letter/b/f4b2a3/32.png) [@Boogly](https://boards.straightdope.com/u/Boogly)\ **Post date:** [January 18, 2014, 8:15am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/11 "2014-01-18T08:15:38Z")
I’d tell them both while they were together. Not to be mean but to let them know what they might face. If they are happy and not hurting others…let them be happy. ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [January 18, 2014, 10:04am UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/12 "2014-01-18T10:04:28Z")
Shame and scandal in the family! [lyrics](http://lyricsplayground.com/alpha/songs/s/shameandscandalinthefamily.shtml) [Blues Busters](http://www.youtube.com/watch?v=8BiNjoKmOh8) Anyway, count me as one who doesn’t care ---
**Author:** ![FriarTed](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/friarted/32/1052_2.png) [@FriarTed](https://boards.straightdope.com/u/FriarTed)\ **Post date:** [January 18, 2014, 1:13pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/13 "2014-01-18T13:13:38Z")
> [@grude](#): > > WAIT! > > Am I reading the OP correctly that there is unintentional incest going on here? Not consensual adult incest, just two people unaware? > > In that case I would discreetly let both parties know what I had heard, I would not publically embarrass them, but would feel an obligation to let them know and they can do what they want. I would not publically reveal the info. > > Letting people engage in unintentional incest is creepy to me. Yeah, this. And I’m not one who is skeeved-out by first cousins. Little genetic risks, no Biblical condemnation. ---
**Author:** ![Mrs.Cake](https://avatars.discourse-cdn.com/v4/letter/m/2acd7d/32.png) [@Mrs.Cake](https://boards.straightdope.com/u/Mrs.Cake)\ **Post date:** [January 18, 2014, 5:08pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/14 "2014-01-18T17:08:28Z")
Eh, no harm being done, why rock the boat, especially if it isn’t your boat to rock? The only reason I could think of to have a quiet word is if there is a chance other people know and will start trumpeting it to the world, catching the happy couple unaware. It’s possible that if you know, they do as well and have already come to terms with it. ---
**Author:** ![Guinastasia](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/guinastasia/32/5751_2.png) [@Guinastasia](https://boards.straightdope.com/u/Guinastasia)\ **Post date:** [January 18, 2014, 5:30pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/15 "2014-01-18T17:30:16Z")
I’d tell them if only because I myself would want to know. After that, it’s up to them. ---
**Author:** ![monstro](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@monstro](https://boards.straightdope.com/u/monstro)\ **Post date:** [January 18, 2014, 6:13pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/16 "2014-01-18T18:13:15Z")
> [@Guinastasia](#): > > I’d tell them if only because I myself would want to know. After that, it’s up to them. Doesn’t it make more sense to tell them if you think that’s what _they_ would want to know? There are a lot of things I wouldn’t want someone to keep secret from me, but what I want doesn’t have any bearing on what another person would want. ---
**Author:** ![Antinor01](https://avatars.discourse-cdn.com/v4/letter/a/ecae2f/32.png) [@Antinor01](https://boards.straightdope.com/u/Antinor01)\ **Post date:** [January 18, 2014, 6:23pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/17 "2014-01-18T18:23:55Z")
> [@monstro](#): > > Doesn’t it make more sense to tell them if you think that’s what _they_ would want to know? There are a lot of things I wouldn’t want someone to keep secret from me, but what I want doesn’t have any bearing on what another person would want. Like I said up thread; considering that the marriage is not legal anywhere in the US, it’s something they need to know before they go through with it. That’s aside from any feelings or what they want to know. ---
**Author:** ![Baker](https://avatars.discourse-cdn.com/v4/letter/b/bb73d2/32.png) [@Baker](https://boards.straightdope.com/u/Baker)\ **Post date:** [January 18, 2014, 6:55pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/18 "2014-01-18T18:55:27Z")
IANAL, so I’m not sure of the legalities involved. These two people genetically are half-siblings, yes. But legally they are first cousins, iif the guy was formally adopted by the aunt. If marriage between first cousins is legal where they live, what is the issue? That someone _else_ is skeeved out about it? I think the whole thing boils down to who else knows, and how would the couple feel about each other if THEY knew. I’d keep my mouth absolutely, completly shut, to anybody, about my knowledge. That way the couple wouldn’t know the I myself knew, and they wouldn’t be on the outs with me if they learned about their own relationship from someone else. It’s like passing on gossip. You ask yourself three questions. Is it true? Is it fair? Is it necessary? If you can’t answer “Yes” to all three, then shut up. ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [January 18, 2014, 7:10pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/19 "2014-01-18T19:10:14Z")
> [@monstro](#): > > One day she reveals to you that she actually has a man. A man who just happens to be ya’lls first cousin. First cousin marriage is very common in the European-American/Christian tradition and also in the Middle Eastern/Islamic tradition, and, so far as I know, it is legal in most states of the United States. If you’re trying to set up some kind of moral or ethical dilemma, you’re going to have to get _much_ closer than that in blood ties—Half-siblings? Uncle-niece? Aunt-nephew? Full siblings? ---
**Author:** ![monstro](https://avatars.discourse-cdn.com/v4/letter/m/ba9def/32.png) [@monstro](https://boards.straightdope.com/u/monstro)\ **Post date:** [January 18, 2014, 7:11pm UTC](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115/20 "2014-01-18T19:11:40Z")
> [@Acsenray](#): > > First cousin marriage is very common in the European-American/Christian tradition and also in the Middle Eastern/Islamic tradition, and, so far as I know, it is legal in most states of the United States. Did you finish reading the OP? [Next page](https://boards.straightdope.com/t/if-your-sibling-was-obliviously-in-love-with-another-sibling-would-you-tell-her/679115.md?page=2)