Why is everyone always so about their sleeping together but the Targaeryans marrying each other doesn't seem to be seen that badly? Is it because they're not married? But really they seem to be judged more harshly. Is it just the twin thing and if they weren't twins just siblings it wouldn't be as bad?

Because with the Targaeryans, only book readers knows about it. I don't believe that was mention in TV either. With Jamie and Cersei, it's in our face.

exactly...

The Targaryen stuff happened in the past.

We actually get to watch Jamie and Cersei bump the uglies.

Defiant1 broke the thread.

And that practice may start up again with Dany & Jon

The reason Jamie and Cersei sleeping together is such a big deal on the show is that they had three kids that Cersei passed off as being Robert's kids and heirs to the throne.
This is one of the most important plot elements to the entire series. It's this secret that started the whole story going. It's a little moot now with all three kids dead, but the only reason the show exists is to see who rules the seven kingdoms at the end.
Ergo, the commonality of incest not withstanding, the Queen having three kids by her brother and passing them off as the King's is a pretty big deal.

when push came to shove, it was a no-braner who Jaime would pick.

That video is causing all the replies after it not to load.....

It is simply what we see versus what we are told. All we see of Targaeryans is Dany, and she seems decent. The fact that there is incest in that family is not front and center, like it is with Cersei and Jamie.

I can post but can't see my post because of that video!

Not sure what was going on with those video posts breaking the thread. But the posts have been deleted.

Sorry, not sure what happened! I posted two YouTube links to clips from the show where characters discuss the Targaryens incest practices.

I think of them like the Egyptian pharaohs who also practiced incest to keep their bloodlines pure.

I'm guessing the last Targarian on the throne going insane probably turned some off to any upsides of incest.

Plus, Cersei's entire claim to the throne is based off her children's claim. If they aren't true Baratheons then her already tenuous grasp gets even weaker.

Incest was always taboo in the Seven Kingdoms. But the Targaryens, even apart from being conquerors, were seen as foreigners. They were tall and beautiful and had silver hair and commanded dragons. They were almost like a higher life form.

The Lannisters, while being a powerful family, are considered regular humans to the people of Westeros.