Like a plant, depression grows because a particular seed (perhaps psychological, such as a loss, or perhaps physical, such as a viral infection) has been planted in soil that is good for growth. The child’s genes or inherited characteristics, the child’s personality and the child’s early experiences can be seen together as the soil in which the seed is planted. Just as both seed and soil are necessary for plant growth (you won’ t get much plant unless you have both of these), so when we look at depression we need to look at both the seeds – the stresses or triggering events – and the nature of the child at the time these events occur. It would be meaningless to say that one or the other is the cause: both are necessary.