I have such bad issues?

i'm the only one in my family with the kind of issues i have. I dont get along with anyone in my family and they all don't like me. i have deep deep issues and i dont know where they come from. I think i am extreeeeeeeemely sensitive and the littlest things affect me. It is so very hard. Do you think this is innate (biological) or is it because i am the middle child? I have absolutely no assertive skills and cannot deal with people reasonably. I am the only one with the problem and i dont know why. My family, on the other hand, is perfectly stable in their mental state and has no problem maintaining friendships and dealing with people. Do you think that there is one scapegoat in a family? The one that everyone picks on and nobody sees it. The one who is treated differently? I cant find the root of the problem all i know is that my emotions are just flooding out of my soul and they and i are completely out of control. What could have caused this? I am literally the only one with this problem in my entire family.