Are you pro or anti cosang?

[CynicalOptimist]

Inbreeding can cause birth defects. However, and as much as people like to use both words interchangeably, incest and inbreeding are not the same thing. The vast majority of people who engage in incest take measures to prevent pregnancy, thereby avoiding the risks and problems associated with inbreeding. Only a miniscule fraction of adult-minor incest cases actually involve inbreeding.

If the purpose of criminalizing incest were to prevent inbreeding and birth defects, it would make more sense to focus exclusively on cases of inbreeding and to only prosecute those who impregnate their close relatives.

Incest, particularly father-daughter incest, can be problematic for other reasons. In her book on father-daughter incest, Diana E. H. Russell notes that some girls were distraught and disgusted at the mere suggestion of sexual contact with a parent. While the stigma may explain some of this reaction, it is likely not the sole explanation. Many people simply find the idea of sexual contact with a parent repulsive and don't want anything to do with their parent's sexuality. Therefore, attributing all negative experiences to the stigma is misguided.

Nevertheless, I don't support the complete criminalization of incest. When it is illegal, children who have had neutral or positive incestuous experiences are also separated from their parents and gaslit into believing they were abused even if they did not originally feel that way. I only want to see cases involving clear abuse of parental power, where the child was coerced and experienced distress and trauma before societal intervention, to be prosecuted.

I remember that I actually wanted my mother to stroke my penis when I was a young child, after I had a positive experience with an older boy, but she didn't want to do it. I'm certain that I wouldn't have felt bad if she had done it.

[RoosterDance]

It's not really about such relationships being inherently harmful, it's really about chances here and trying to grow a healthy population.

Agreed. Though it turns out the issue is more nuanced than all that.
Also, that article you linked is difficult to read. It glosses over a lot of things and is very repetitive. I prefer the Wikipedia article. It provides a more balanced perspective, is much more succinct, and even has a couple visual aids.
Anyway, I also did some more research and...

Basically, If your family has a history of genetic disorder, then breeding within that family increases the chances of that disorder being passed onto the offspring, as both parents are likely to be carriers of the disorder gene.

My statement here was an oversimplification, but the main point still holds. You can't pass on disorder genes if you don't have them. To explain in a bit more detail, they key points are thus:

• Inbreeding increases the chance of recessive genes being expressed in the offspring. This is because in order for offspring to express recessive traits, both parents must have the recessive gene. In contrast, to express a dominant trait, only one parent needs the dominant gene. If both parents have similar genes, they they are likely to have the same recessive genes. Increased recessive traits can be a good thing or bad thing entirely dependent on the trait itself.
• Most genetic disorders are caused by recessive genes. I assume this is because any disorders caused by dominant genes are naturally selected out of populations pretty quickly.
• For this reason, yes inbreeding does increase the chances of genetic disorder. And the chance further increases with multiple generations of it. But these chances have been massively overblown. Again, you need the have the gene in the first place to pass it on. Even if you do, as long as you're not mating with someone who is obviously affected by genetic disorder, the chances of offspring being born with disorder don't get higher than around 25% due to how punnet squares work.
  
  It's worth noting that all of this applies to beneficial recessive traits as well, like the O- blood type or non-baldness in males. But the vast majority of these recessive traits are not going to have a profound effect at all.

You also speak of problems caused by inbreeding populations. Yes, a lack of genetic diversity can cause issues for populations. But in contract to issues that affect only individuals, these problems are much more easily solved. Diversity can be introduced, or the population can disperse. Still, I imagine much of these same problems are faced by regions that have become very homogenous even without inbreeding. I'm thinking of the non-touristy areas of Asia and Africa.

Ever heard of the Whittakers?

I have not heard of the Whitakers. Thank you for showing me this.
Despite the title of that video, this is far from the most inbred family I've ever heard of. And those families are doing just fine.
It looks like the entire famous part of that family is the result of just one couple of cousins. It seems clear to me that those cousins had lost the genetic lottery and were not fit for inbreeding. Probably not fit for outbreeding either, yet they kept doing it. It's a shame then that people then attributed the problem to inbreeding in general rather than to those specific people.

When I think about it, other possibilities exist too. Maybe their problem doesn't have anything to do with inbreeding or genetics at all. Maybe the mother was just really careless while pregnant. Maybe the father was abusive to his constantly-pregnant wife. After all, there's probably a reason they had 15 children while the rest of their family did not, at least not as far as we're aware. I'd say this requires more investigation, alas the window for that has likely passed.

I'll have to do more research into those other examples you cited.