Imbalance

Muscles grow by being used, torn, and trained. Due to the nature of many sports, imbalanced muscle growth is basically a given. If you have a dominant hand or leg that constantly does one task, it'll obvious develop more than you're non-dominant arm/leg.

Over the years, I've done a lot of sport including many that contribute to imbalanced muscle growth.

The list includes handball, soccer, volleyball, ping pong, and I also dabbled a bit in basketball and tennis.

For me, I only really noticed it whilst performing the grabbing hands behind back stretch. With the left hand on the bottom version, I could relatively easily grab my hands together. With my right hand on the bottom, I couldn't even touch my fingertips without assistance.