Siblings hate on me for, according to them, being a narcissist.

I recently became the first of my family to have been accepted into university, so you can understand how proud my parents have been..however my siblings, is another issue. Since GCSEs, I remember my siblings always criticising me. I remember back when I was in year 9 and most of year 10, I was in the phase where I wasn't really bothered about school and didn't really care about my grades. When I used to have bad grades written on my reports, my eldest brother especially, would laugh at me and call me an idiot blah blah blah. During year 11, I really turned around and put my head down and came out with some fairly good results, I didn't get straight As, mainly got Bs but I was still proud of my achievements, regardless. So when my parents basically told me how proud they were of me etc etc and encouraged my siblings to work hard so they could get good results, it got my siblings telling me that i thought too much of myself. Me, my older brother (21) and my young sister (17) are the one ones who've already completed our GCSE year so far and I did better than both of them and when I told my sister who is 17 this, she got annoyed. I didn't do it to put her down because I remember I used to tell her constantly to put her head down and stop chasing after guys and talking on the phone all the time, to spend some time focusing on her studies because it will go a long way, which she obviously didn't do so that really wasn't my fault because i tried to encourage her as much as I could, so that when I did confront her about her results, it p'd her off. My A-level results were also relatively good too and I guess this interlinks to her GCSEs because I got my results before she got hers..and I have told her that "I'm at university now, I've worked hard and look I've got a laptop as a reward. Work hard and you'll be rewarded" but she always feels like I'm just rubbing it in her face - which I'm honestly not. I've even told her that I'm just saying this because I care about her. My older brother tends to share the same views as her, he had no interest in his studies and spent around 3/34 years at 6form (whereas I spent 2) because he was also retaking GCSEs (whereas I re-took none) and basically he went to a local college, then after finishing there, spent like two/three years at home doing nothing and then wanted to apply to a college (which he classes as a uni) during the time I was applying for uni..now he basically hates it when my dad tells him that i've gotten somewhere from working hard and all he's doing is moving from college to college and not focusing on his work which is actually true - he tends to go there to play games online rather than doing his work so you can understand why he thinks its being rubbed in his face..

so what i'm saying is, how do i explain to them that i'm not working hard and aiming high etc etc, to rub it in their faces and make them feel bad? I'm not trying to suck up to my parents and be their favourite - i'm just somebody who works hard at what i do, which they don't bother doing, and then i get criticised for thinking too much of myself. help? sorry for the rant, realise it could've been shorter but it's written now..