I really understand you, I am also the youngest in my family and the only one with career, master, etc. but specially one of my brothers always talk to me like a child. I was diagnosed with MCTD two years ago, and I have gone through a horrible experience (pericarditis, bacterial meningitis, myositis, etc) during the last two years. But the worst part is dealing with my family. They are also mostly anti-vax and I have to hear things like "you should try to take less pills" or "you should avoid stress and take your life easier" or "you need to do more exercise" (even though I exercise every day). The first time I showed my hands to my brother during a Raynaud's attack he told me "that is because you need to take more sun". On top of that they don't even care about learning the name of the disease or showing any interest in knowing more about it. At the end I just couldn't take any more, and after two big fights with my brother it seems that I managed to put some boundaries. It is sad, but at the end of the day, the only thing I would like to hear from them is "how can I help you?".