Is it bad that i hate my half sister's cause there MIXED? and why am i treated differently?

ok im 16 years old and my father passed away when i was 2 and my mom got remarried when i was 5 to a white man (im black). and ive never liked my step dad, when i was 6 they had twins jessie and parker(10yrs). and its like they have the best of both worlds, good hair ,light skin and all of that. and when theres a family reunion on my stepdads side i can't go..because my mom feels that it would be to awkward for me, they get all the clothes they want, and they even go to private schools while im stuck going to a public school. my step dad sends them across the country or world every summer to go visit family,beach,whatever. while im stuck at home. and whenever i argue with my sister's he'll jump in and defend them and tell me to go to my room, and my mom doesnt do anything to defend me. and they even get the best christmas presents! why am i treated so differently?? is it bad that i hate my sisterS?? ill be honest sometimes when my parents arent home i beat them up, because everybody likes them better cause there mixed and my sister are brats they dont do anything and just love to get me in trouble