The reason there isn't any hydrokinesis or aerokinesis is because fire and lightning are energy-based forces. Otherwise, hydrokinesis is just someone controlling water, not creating it out of their own energy. Crytokinesis is merely using one's energy to force atoms to stop their movement, thus the area would lose heat.
Some children are more susceptible to contacts with spirits because their energy is more flexible, or malleable, and because children tend to be more trusting of strangers, they let the spirits harness their energy.