As trees grow they need occasional trimming, sometimes it’s to promote healthy growth and other times it’s to mitigate risk. Trees will often grow in the direction of natural sunlight. This means that if a tree is completely alone and out in the open it should grow evenly in all directions as its able to absorb sunlight from all directions equally throughout the day. If a tree is located near a structure or other trees where part of its access to light is obstructed it will over time lean and grow its branches in the direction. This will cause the tree to grow unevenly and will ultimately result damage or deformation.