If it was from seed, then it might just be a natural variation in the plant. Is it just the branches or is the trunk 'weeping'? Is it staked? Check that any tree ties aren't cutting into the trunk as it will expand over the years. Tight ties will restrict water flow up the stem.

Thanks so much for this. It is the leader of tree that has flopped over along with all the branches. The tree was planted two years ago as a tree and has been very healthy and I don't think it is a sport. It is staked with proper flat tree ties but the tie is quite tight, and although not cutting into the trunk, I did wonder if the stake is preventing the roots from developing and have loosened this now. Do you think it might right itself at all?

no it probably wont but i believe if you get in touch with a bonzei expert you can force it back strate with wire done properly . its a gradual procses if at all possible.