<human>: Can you summarize the given text in a few sentences?

My sister just turned 25, and she's been with a few other gents before this guy for much longer and wound up breaking up. I've been with my girlfriend for nearly five years now (and we're a good amount younger so it doesn't really make sense to get engaged any time soon). Even if the engagement winds up being for a good long while and they don't get married for two years or so, I feel like she's rushing because she's scared she won't find Mr. Right. She does seem to be happier with this guy way more than any previous gents, and he actually is a genuinely nice guy, I'm very happy he's with my sister, so respectful. His upbringing wasn't the best because he had a single mother bringing him and his three sisters up on her own, and she was a shitty parent. He tries his best all the time to show that he's more than his upbringing. So at the end of the day, I'm incredibly happy for my sister and my future brother in-law, but both my sister and her fiance never got much past high school. I know that sounds incredibly condescending or mean to a lot of you, but I'm worried that my future niece or nephew will lack motivation in school because I know for a fact that my sister feels that she did perfectly well after dropping out of college after a year (even though she struggled harshly and picked up horrible and expensive habits, some of which she still have). The fiance basically seems to bend to every whim that my sister pushes him, so seeing him interject into how my sister wants to raise her kids doesn't seem likely. I'm just scared because I know how an intelligent upbringing can be so stimulating compared to being glued to a television for your entire adolescence. 

Click the link to get an idea of how he types (what he wrote on my sister's fb wall):
<bot>: Sister got engaged to a guy after 8 months, they're both academically lazy/irresponsible;scared my future niece/nephew will watch nascar and not aspire to be much.