What does it mean when your Parents ignore your existence?

I am a middle sibling of a large family. Throughout my life my parents have ignored me. They will spend time with my siblings but will intentionally leave me out. I have been married for 27 years now and they have never invited us over for dinner, etc. I quit calling when my mother expressed disgust at hearing my voice. People that know my siblings have relayed comments that they have said about me and my husband. I have expressed my feelings to my parents but it did not change anything. Recently, and to stay in touch with my adult children, we all joined facebook. I noticed that my parents and sibilings had joined as well. I waited to see if they would reach out to me. They have not. However, they have reached out to my eldest child. So, what message are they sending me? I am not surprised as they have treated me this way my entire life. What does it mean when your parents ignore your existence?