Gene families are groups of related genes that share a common ancestor and often have similar functions. These genes arise through processes like duplication, where a gene is copied, and mutations can lead to variations in function over time. Gene families can be found across different species, highlighting evolutionary relationships. The study of gene families helps scientists understand how genes evolve and adapt to different environments. For example, the hemoglobin gene family includes various genes responsible for oxygen transport in different organisms. Analyzing these families can provide insights into genetic diseases and the development of new therapies.