You are looking at generational trauma from a worldly point of view not a spiritual point of view. Your spirit is not limited to what is, but can interact with past, present, future and all possible alternatives. Even on this limited 3D earthly plane you can heal others trauma by example, through intellectual interaction, loving touch and mere presence. Reiki, massage, counseling and collective worship all seek to accomplish this kind of healing. Please don't limit yourself so severely, you have a much greater effect on the world and the people around you than you can possibly know.