Feels like I'm adopted?

I honestly feel like I'm adopted the way my parents treat me you wouldn't think I was their child. I have two sisters are my parents have never treated them like ****, when I was 8 years old their was this word I hated being called, can't remember the exact word and my parents used to deliberately call me it and wind me up to the point I would punch myself in the face it got so bad I actually smashed a clock on my nose and still got the scar from that still. My sisters hated being called something my parents wouldn't call them it, but for some reason that didn't apply to me. I've also always been blamed for stuff, something went wrong, my fault. Whenever I go out with my "family" I always feel isolated and unwanted because my two sisters are together my mum and dad are together and then there is me just tagging along, unwanted. I get blamed and told of for stuff my sisters get away with we recently brought a new sofa and I had my legs up on it and my dad told my mum (he doesn't tell me because he hates me) and so my mum told me to take them off shouting at me my sister had her legs up and they didn't say nothing! My dad has hated me for as long as I remember I actually spoke to him about why he treats/treated me as we don't talk no more and he said because his dad treated him like that, I've I ever have a son I wouldn't treat him like my dad treated me that's just a rubbish excuse