<human>: Hey Reddit, I would just like to get some of your perspectives on an issue that is going down in my family regarding my sister, and if what she's doing is normal behaviour or just a phase that is typical to go through.

My sister, who is 19, has just done her first year of University and ever since it started in September she has been extremely distant with my family, to the point where since Christmas we've only seen her twice and she even didn't show up to my mother's birthday.

I understand that this is semi-normal to not see your family as much while in University/College but I was under the impression that was due to the whole distance and travel issue, however, my sister didn't leave town for University, she currently lives around 20-30 minutes away from home.

The only reason why I'm asking this now is because a few hours ago she was having a conversation with my mother over Facebook which resulted in my mum in tears for hours because my sister said the reason she hasn't been coming home was because of her, and I quote, "terrible childhood". Which, I'm sorry, is a complete lie. My sister is only 1.5 years older than me so we basically had the same childhood and it has really pissed me off that she has made my parents feel like complete failures, given that they've sacrificed everything for us after having us at such a young age. 

I'm sorry but I just can't help but think she's being, pardon my French, an ungrateful bastard.

Could you distill the essence of the text into 1-3 sentences?
<bot>: Sister has my mother in tears after saying the reason she doesn't come to visit was because of her "terrible childhood" and seem to be abandoning my family.