Genetic drift

Genetic drift is when a species’ genes change by accident over time. Each time a species has babies, it randomly inherits a mix of its parents’ genes, and this randomly mixing of genes happens over and over. That is genetic drift. It's kind of like when you close your eyes and stick your hand into a bowl full of marbles, you have a pretty good chance of picking up different marbles each time. That's genetic drift - things changing randomly and over time.