I'm nearly 20, living at home while I'm at uni, working casually to pay my uni bills and other expenses.

My mum and I have never been close, I have always felt like my little sister is the favourite child. As kids I was always getting into trouble as my sister went through a very long "tattle-tale" phase which lasted until she was at least 12 (my mum never did anything about it except to yell at me thereby enabling it to happen frequently). I wasn't a bad kid, I just made mistakes like all kids do - dragging dirt into the house accidentally that sort of thing. I was always labeled the "problem child" by my mum. She used to talk badly about me openly whether I was in the room or not to anyone who would listen. As a toddler I used to have temper tantrums like many kids but because she was a first time mum and didn't know what to do, she used to go on and on about them but she always made out that I did it on purpose as a direct attack on her and that it was abnormal for a toddler to have temper tantrums, that was until I looked it up and found out that it's normal.

My Mum came from a family where her younger brother was idolized as the first son and given gifts of cars etc which my Mum never got. My grandmother was very proud of her unique colour red hair and when I was born with that same colour hair (which even in the family only occurs once every second generation) she was so proud, she would come over and spend lots time with me while my Mum was at work to spoil me. When my Mum and Dad decided to leave South Africa because of the problems over there (me age 3) they became really horrible towards my Mum because they felt she was taking me away from them. For example, they wrote in Christmas cards to all of our relatives that Mum had mental problems, which Mum later found out about.

Growing up I thought the reason Mum didn't like me was because my red hair reminded her of her Mum and all the horrible things they said to her and about her as a result of her leaving South Africa. I feel like I'm the family scapegoat and I feel like nothing I do is ever right or good enough for either of them. My Dad came from a family where the kids where seen and not heard and I have always been somewhat headstrong and stubborn so that doesn't help.

Whenever something goes wrong, I always get the blame for it. My Mum admitted once that it's because I'm the oldest but my sister is nearly 16 and sometimes it's just as much her fault as mine but I'm still the one who gets in trouble for it. I don't drink or smoke or do drugs, I do pretty well in school and uni and I always pick boyfriends who are decent people. Basically I'm so scared of doing the wrong thing and getting in trouble I have missed out on making a lot of the mistakes people my age make. It's because they punish me emotionally as well as yelling and all of the usual things. When I get in trouble for something, they are extra nice to my sister and they practically bark orders at me and it goes on for days depending on what I've done. When I get up in the morning in my sister's school holidays, the first thing I hear is "sssshhh!!" or "don't wake up Natalie" in an angry voice even if I'm not making any noise. My Mum has often told me that she wished I could move out or she wished she could afford boarding school (back when I was in high school). I went to see someone once and they said that it is part of South African culture to yell a lot and say things like that which aren't really meant.

My sister doesn't help either, she never defends me when they're being unreasonable. She just sits quietly and lets me take it.

Nowadays things are a little better but the same problems still arise and it just brings everything back to the surface for me - all the times I felt completely alone and left out as a kid. That things are a little better now doesn't help me either because I never know where I stand - do they want me around or not? I'm constantly afraid to let them in because of these outbreaks, I feel really awkward and out of place if they show affection which is very rare because they know I don't like it (but they don't know it's because I think they're just going to use it against me the next time they punish me emotionally for something).

I know I probably sound dramatic or ungrateful sometimes but it's only because I'm depressed about this and I fear that it's something that's going to hang over my shoulder for the rest of my life. What do you think?

Sounds like maybe your mom is jealous and miserable and taking it out on you.
Since her brother was first born and favored may be some of the reason she has resentment toward you. I think your sister doesn't defend you because she sees it as a tug of war of affection, like if they are picking on you she is soaking it up as positive attention for herself.
All you can do is your best. Get ahead in life where you don't have to worry what they think of you. Hopefully eventually they will realize that they should treat you better.
I don't know if trying to talk to them and work it out would do any good.