Katrina Stack: 23, Micanopy, Florida Twitter: @katrinaaoxx Bad Blood: Anna Stack, 25, Orlando, Florida Twitter: @stackanna Sisters, Katrina and Anna Stack have a deeply rooted sibling rivalry and dramatically butt heads over everything. Usually prompted by Anna’s mood swings and Katrina’s selfish tendencies, their rivalry  launches long bouts of silence between the two and resentment toward one another.