Who is after the twins and why would anyone want to hurt them?

Jean and the others didn't have the answers but they knew that without the twins the world would be in real danger, so it was up to them to keep one step in front of whoever was after the twins.

Jenny and Bunda didn't think they were special, they just thought everyone was like them until someone wanted to take them away from Jean, then they meet John and Sam and the adventures start.