What is the text evidence or author comments that Jon and Sansa were not close as children? This seems like a silly question because the accepted view is that they were not close. But what is the actual book evidence. Or is it the lack of book evidence, as in them never sharing a scene? The example of Sansa saying Jon is jealous of Joffery because he is a bastard is evidence of typical sibling stuff. Jon made a jerky comment. Sansa heard about it and had a more jerky comeback.
I don’t know about about author comments but as far as the text goes, it’s not just that they have never shared a scene.
From the very start, Jon and Sansa are set up as being on opposite sides of the Stark family. They exist in different worlds - Jon is the outsider perpetually struggling with feelings of alienation and not knowing his place in the world; Sansa is very settled in her identity and in her current and future place in society. Jon is the most Northern of his siblings whether in looks, attitude, cultural leaning or religion; Sansa is the most Southern. Jon wants Winterfell with every fiber of his being and is tormented because he knows he doesn’t belong and can’t stay, Sansa wants to leave Winterfell for the glamorous south. Jon is heavily associated with Ned; Sansa with Catelyn. Jon is the stain on Ned’s honor, the Bastard of Winterfell; Sansa, in all her beauty and well-mannered glory, is the prize of Winterfell.
The association with Catelyn in particular is important because Sansa idolizes her mother and strives to be a lady like her which led to her taking in Cat’s attitude and mannerisms as her own. Her worldview is shaped by Catelyn and Septa Mordane’s teachings. Which means she absorbs her mother’s view of Jon unlike her siblings, and it clearly colors how she thinks of him. That’s not to say she hates Jon or anything, but it’s obvious that she does not see him as her family in the way the rest of her siblings are. She always makes the distinction in referring to hims as her half-brother and even corrects Arya when she refers to him as their brother. Even in AFFC, when she thinks of how Jon is the only family remaining to her and yearns to see him, she still struggles with that perspective as she thinks that he is only her half-brother.
How Sansa brings up Jon in the context of thinking about Arya and how different they are in the first book is also telling. Sansa looks down on Arya for not behaving like a proper lady or conforming to gender roles. She is upset Arya is not like Myrcella and can’t understand how two sisters can be so different - and she promptly thinks of how it would be easier for her to understand if Arya was a bastard like Jon. That speaks a lot of what Sansa thinks of the boundaries of a proper relationship between her and a bastard sibling, and the kind of behavior she expects from bastards.
Moreover, the lack of interaction between Jon and Sansa absolutely matters. We do not get a lot of scenes between the Starklings in present time but the fact that Sansa is the one sibling we did not see Jon saying goodbye to, other than the toddler Rickon, really stands out. More importantly, we learned a lot about the kind of relationship the Starklings have with each other through their recollections after they go their separate way - and Jon and Sansa are each the sibling the other thinks least of, and when they do, it almost always happens in the context of them thinking about all of their siblings or when one is specifically brought up in front of the other. Contrast that with how Jon often thinks of Arya and Robb and Bran, or how Sansa thinks of Robb and Bran, and even Arya who we know she isn’t close to at all.
And no, Sansa’s comment about Jon being jealous of Joffrey because he is a bastard isn’t typical sibling stuff. This isn’t really about Sansa defending Joffrey with whom she is half in love with already. She is so matter-of-fact about Jon’s comment being born of jealousy. That’s a truth to her, not an opinion, because that’s what she has been taught to expect from bastards.