Worries for my sister

Hey there, my name is Michas, 22, and I live in Denmark Europe.
I have a cute but unbelievably shy sister at 11 years of age. To explain my concerns for her, I need to explain a bit about my story, as we are practically alike, personally wise, opposed to my younger brother at 19.
I have some social phobia with everything that it means. On my mother’s side we are very paranoid and think things and fears waaay to far out (tripping constantly). This especially started to affect me when I got into adolescence. Here, my family moved from the city I had always lived in, the friends I had always had and the school I had always gone to. My life crashed. My insecurity coupled with the need to make new social contacts made me an easy target for bullying and the scars are still there. Well, not as horrifying images, but as a constant feeling of not doing “good enough”. I coped, somehow.. When I got out of school the bullying stopped. I started on another school (resembling the last grades 10-12 of high school) but was the loner all the way through.
During my senior year my mom had a blood clutt in her brain and fell very ill. I barely remember much from the times where I drove from our city to the hospital just to see her completely disabled and “weird”. One day she suddenly got better and was able to return home. All the left side of her body was incapacitated tho’, so often she drooled from one side of her mouth, had to be carried around and she said some very weird stuff… I was kind of scary. However, I was mature enough to understand what had happened and was going on and I helped the best I could. My mother situation never really affected me much, apart from feeling her pain.
Then I moved from my parents at an age of 19 and started living the LIFE! …Drinking every weekend, smoking weed every day, soon moving on to other, harder drugs, partying day out day in for weeks at a time. Long story short: I didn’t know how to process my traumas, much less live my life.
Finally, just eight months ago I had to move back to my parents place because of economical problems. It was the best thing I ever did. I saw everything in another perspective after being away and isolated for so long. I have been “fixing” myself ever since. My worst problem now is seeing my sister going down the same dark, dark road that I went by…
Returning to the case with my mother; I was not that badly affected, but the story is a completely different one with my sister… She lost her mom that morning the ambulance people came to get her. She never really saw her again. My sister started acting towards her like children of divorced parents act towards their fathers/mothers new relationship, complete rejection and disrespect. Of course the fact that my mom had no understanding of the situation at hand and tried to live life as she had always been (impossible in every way) and kind of expected that my 6 year old sister would just accept her, although she was like a different person. To this day, five years later and even though my mom actually regained all of her great personality (still somewhat disabled though), my sister is still disrespectful towards her, albeit not as grim as she used to be. There is so much that should have been handled differently…
She is 11 now and extremely self conscious to the point of it being paranoid. She is obsessed with “fitting in”. My brother is a lot like I was when I was 19, without the paranoia and negative social phobia stuff. He has my father’s social genes I guess He doesn’t think that far, is very naive but very proud and conceited. He is also a great and loyal guy
He teases my sister, and she teases back, day out and day in. It’s never bullying, but sometimes it’s quite harsh. Irony is used on sarcasm. Irony is used heavily on both sides. My sister understands that it is for fun. However, I only see her getting worse and worse, and some of the things she tries to “fix” about herself to look “normal” are ideas planted by my brother during his teasing… It’s something like this, just one example: He teases her about her posture, and she teases back with his nose. A few days later he commends on her posture again, telling her that she could look better and taller if she put her shoulders differently and stretched her back – which is true for walking on the catwalk but really not necessary for feeling comfortable and normal.
Then today, she asked me if her posture was “correct” and I told her that whichever way she feels good is OK. This answer is not good enough for her and she goes to my brother and he gives her the same answer he gave her a month or two ago (which was when he teased her with it). Then I brake in, I see what is happening, and try to tell her that she doesn’t need to have her back like that to look normal, and that she is to be just as she feels is good. She then replies to me: “But I don’t know how that is…” and asks my brother again…
When I try to confront my brother about it he goes in complete defense mode and tells me I am “taking everything waaaay to seriously”. Well, maybe I am. But I think the possibility that I am right, even if it was one to a million, is worth asking professionals for advice about, especially when considering my own bad “outcome”.
I don’t know if I am right or wrong about this, my dad thinks I overreact, but this constant, although for-fun, teasing seems waaay out of hand, and not constructive at all for a family…

What do you think? Am I dead wrong? Or right? Or is it not possible to say from the above? Should we consider talking to a professional?

It's difficult for me to respond to what you've shared, because of the amount of grief, empathy and other reactions such information elicits. As Decius so accurately described, it is extremely detrimental for a young female's psyche to endure such negativity about her physical body. Though your sister may act like she thinks the 'jokes' are fun and games, they are definitely not and both her and your brother recognize this subconsciously, and perhaps even consciously.

I think Decius explained all the main things that should be taken into account, so I need not repeat them. However, being a female myself I can provide you with some insight from my own life to aid demonstrating how serious being physically demeaned can be for a young female.

During the ages of 10-16 my body went through changes due to puberty - developing breasts, hormonal changes, menstruation, pubic/underarm hair, thicker eyebrows. I no longer looked as 'pretty' and 'clean' as I had prior to these changes. Mind you, I don't recall knowing that I looked pretty because I never focused on such things before the age of 10. But because of teasing that I experienced at the hands of family (brother, cousin brothers) and at school from guys and girls, I started to feel very ugly. I still even now, refer to that period of my life as my 'ugly' stage - and even though I know that that descriptor is a result of social fallacies, I cannot even now emotionally believe that I was not ugly back then.

I also developed hairy legs and more noticeable facial hair during that age and was teased extensively by certain individuals about my hairy legs. I still have not healed myself of this torture, even though I firmly believe that a woman with hair on her legs is no less valuable and no less beautiful than a man with hair on his legs. Such psychological torture and pain experienced from those years of abuse becomes deep rooted, and even an individual such as me (I have less insecurity now and more confidence than the average female), I still have not alleviated myself of the effects of being teased about the hair on my legs, which occurred over 14 years ago.

There is no possibility that your sister is not being damaged/negatively affected by your brother's abuse/teasing, and the example of the posture situation you described is proof. Your sister saying 'But I don’t know how that is' is very real, she has been ingrained with falsehoods that now prevent her from knowing what feels correct to her body and what is not - she is relying on the external world to guide her because the external world is saying to her that the way she is naturally is not acceptable. Such things create deep self loathing, leads to depression and can pave the way for other detrimental life experiences.

So what can you do to help the situation? Unfortunately the same negative comments that your brother is making towards your sister, are suggestions that society, culture and media make constantly to women. Although opposing these societal negativities is a broader problem, I think having such negative comments be be thrown at a person from someone they respect is usually be far more damaging and can result in making your sister more susceptible to social pressures. Again, I agree with Decius - you could educate your brother about these things and if he doesn't stop then it's a choice that he is making and he gains something by demeaning her.

And in regards to helping your sister directly - I find that providing information is usually one of the best things to do. Inform her about your beliefs about how you believe your brother is wrong in teasing her, why you think it's unhealthy. If you genuinely agree that women are portrayed negatively in society, then express that to her that. Perhaps if she connects to your expressions, then as friends the two of you could explore these things together. Having such a friendship with someone could help her tremendously. Of course, if you are going to try initiating such interactions with her, for own emotional well being you should be aware that your sister may completely reject what you have to say. I have found that sometimes women react very badly to the very information that can help free them - almost as though the pain they feel when presented with information that empathizes with their suffering, is too great and causes them so much grief that they become angry and reject the information and the person presenting it.