CONSENSUAL incest is not wrong. (Abuse victims: being abused by a relative does not make it wrong for others to have consensual incest, any more than rape by a stranger makes all sex wrong. Sex and assault/molestation are two different things.) An aversion became common in humans to aid in population growth so that one disease wouldn't wipe out the human race. That's not a problem anymore.
Consensual incest is very common. You know others who have been involved, whether you know it or not.
There is no rational moral reason for keeping laws or taboos against consensual incest. Personal disgust or religion is only a reason why one person would not want to personally engage in what I call consanguinamory, not why someone else shouldn't do it. An adult should be free to share love, sex, residence, and marriage with ANY consenting adults. Youthful experimentation between close relatives close in age is not uncommon, and there are more people than you'd think out there who are in lifelong healthy, happy relationships with a close relative. It isn't for everyone, but we're not all going to want to have each other's love lives, now are we?
Some people try to justify their prejudice against consanguineous sex and marriage by being part-time eugenicists and saying that such relationships inevitably lead to “mutant” or “deformed” babies. This argument can be refuted on several fronts. 1. Some consanguineous relationships involve only people of the same gender. 2. Not all mixed-gender relationships birth biological children. 3. Most births to consanguineous parents do not produce children with significant birth defects or other genetic problems; while births to other parents do sometimes have birth defects. 4. We don’t prevent other people from marrying or deny them their reproductive rights based on increased odds of passing along a genetic problem or inherited disease. It is true that in general, children born to consanguineous parents have an increased chance of these problems than those born to nonconsanguineous parents, but the odds are still minimal. Unless someone is willing to deny reproductive rights and medical privacy to others and force everyone to take genetic tests and bar carriers and the congenitally disabled and women over 35 from having children, then equal protection principles prevent this from being a justification to bar this freedom of association and freedom to marry.
Some say "Your sibling should not be your lover." That is not a reason. It begs the question. Many people have many relationships that have more than one aspect. Some women say their sister is their best friend. Why can’t their sister be a wife, too?
Some say “There is a power differential.” This applies least of all to siblings or cousins who are close in age, but even where the power differential exists, it is not a justification for denying this freedom to sex or to marry. There is a power differential in just about any relationship, sometimes an enormous power differential. To question if consent is truly possible in these cases is insulting and demeaning.
Some say “There are so many people outside of your family." There are plenty of people within one’s own race, too, but that is no reason to ban interracial marriage. So, this isn't a good reason either.
Some people who say it is wrong seem to have no problem with complete strangers having sex. So get over it, all of you who want your personal disgust to dictate the lives of others.
Many allies chimed in. BC_Programming even wrote...
I think it's a tad odd myself but in a lot of places it's illegal which is pretty silly. The issue is that incest is usually automatically connected with rape or paedophilia in most peoples minds, but really it shouldn't be.In the end, nobody gave a reason to deny equality that I haven't countered here.
I originally wanted to draft a post showing why it was "wrong" but of course was unable to actually come up with any good reasons. To try to articulate why incest should be viewed as inherently wrong is difficult and there’s no clear argument.
The only thing that I could really come up with is "it's not natural" but that's a really stupid reason. Plastic isn't natural either but it isn't morally wrong. It's fucking plastic.
Aside from that, it's just the standard "inbreeding" argument given earlier, but that is something of a strawman, isn't it? After all, the same argument could be used to prevent people with disabilities or who carry specific genes from reproducing, too. More importantly, incest!=reproduction. Have you had ten children with every girlfriend/boyfriend you've ever had? No, of course not. Since we don't condemn or restrict (or make intimate relationships between) people at increased risk of having disabled children, clearly this reason holds no weight either.
Personally, I find the idea of incestuous relationships somewhat repugnant, but in examining that knee-jerk reaction to try to find a real, logical reason for it, I can't find any, and those that were stated (and restated and argued by myself here) are invalid in this case. This doesn't change how I feel about it, which makes me think maybe there is some sort of instinctual aversion to the idea, as somebody else said. This would certainly make sense and is definitely visible in animals. On the other hand, it could very well be a case of Human culture typically preferring exogamous pairings. Additionally, and in something of an interesting twist, while every human culture has some sort of "taboo" on incestuous relationships, the actual definitions vary.
Note that for incestuous relationships to result in problems, it would have to be done for a very long period over many generations, with very little new genetic information being added to the gene pool. This, fundamentally, does not make a specific instance inherently or morally "wrong" any more than it would be wrong for a person with cerebral palsy to have children.
Another interesting explanation is an effect that seems to manifest itself through early life, and is theorized to be a psychological effect through which people that live in close domestic proximity during the first few years of their lives become desensitized to later sexual attraction. This is sort of the "instinct" provided; and evidence can be seen with adopted children (who are otherwise unrelated to birth children from those parents or other adopted children) and the reverse, where the early years of a persons life are away from one relative, and after several years they are reintroduced, and feel attraction towards that individual. As far as the "instinct" is concerned, they aren't related so they are, err... "fair game" I guess.