Never heard of ‘protect sister mode’ ???
An obvious, but NSFW link: Fix “hxxp://sexylosers.com/002.html” manually. The classic “A Galaxy Far Far Away” strip back from 1999.
And regarding Luke’s previous experience - what do you think why Camie called him “Wormie”?
Let’s not forget the kiss “for luck” before swinging over the chasm in Death Star One in the original. Zero chemistry. Like kissing your sister. Lucas may not have intended them to be related at this point, but he might as well have. ESB kiss, like everyone here says, even Luke knew it was just to piss Han off.
That’s about what I thought. And I’m sure Lucas wasn’t thinking “Hey, ew, they’re brother and sister!” in 1977 when A New Hope premiered.
I have just seen the youtube video, linked down thread, and YES, the enjoyment of the moment certainly seems to go beyond connecting with Leia wanting to piss “Yoyo” off. And elsewhere there is the snippet of dialog adding to the case that Luke definitely had strong-enough interest in her.
Luke, the bumfuck farmboy he is, would definitely have the hots for the gorgeous, rich, badass princess he’s rescusing.
Leia, on the other hand, probably thinks of him as just another soldier, and then later as nothing more than a friend.
What’s the reference here?
I believe it’s from a obscure animated show called BoJack Horseman, whose developers will be delighted Sr Siete is a viewer as that doubles their fanbase. 
That gave me enough to figure the rest of for myself. For anyone that cares, here’s the synopsis:
Thank you for linking that photo! It’s exactly what I was going to reference in response to the “desexed” comment. That scene was a milestone in my life (I was 11 years old), and had a very “get the heart racing” effect on my young self. Perhaps the effect that shot — with the pretty girl in prison — had on me was a precursor to the interest in BDSM I discovered 2-3 years later. Interestingly, that scene affected me exactly the same way when the movies were re-released in 1996, and I was 30 years old.
Oddly, though, the “slave Leia in a gold bikini” scenes never did anything for me at all. In hindsight, I suspect Ms. Fisher’s drug and alcohol use (of which I was not aware at the time) had taken a subtle toll on her appearance, and I picked up on it, subliminally, and she just didn’t have that “spark” she had in the first movie.
Oh, the slavegirl outfit was plenty hot, and those scenes were among the top three for Leia hotness. But the other two were both in the original, the prison bunk and the medals ceremony (which incidentally proves that you don’t need to be wearing skimpy clothes to be sexy).
There being no “No” vote, I voted for brandy.
In the first bio of Lucas, out before RotJ, they mentioned that when he was a kid he wrote lots of stories about a hero rescuing his sister. So the family thing might have come from somewhere.
When Luke saw the holographic image, he thought Leia was hot. But when he actually met her his incipient Force power told him that she was off limits - which explains his lack of interest. He needled Han - like Han needled him - but Luke never seemed to be in serious competition for her.
When Obiwan tells Luke the secret he follows it up with a line which I can’t remember exactly but which is odd. It definitely does not sound like Obiwan has sensed Luke thinking “better stop thinking about boinking her now.”
There is a generational divide too. There are now people that have seen the movies in the weird order of III before IV, so they know they are related going in. That kiss on Hoth has got to look like a really odd choice to them.
