Gemma and Kate Harding are sisters, they look different because Kate was adopted into Gemmas' family when they were both just toddlers.They are very close. Once the ship crashed they were able to swim to safety. It's been so long since they've seen anyone who could help them that Kate has given up hope, Gemma hasn't, she's really optimistic that they'll find other survivors and become a great team. Let's prove Kate wrong! #USISLANDCHALLENGE #USISLAND