A family tree is a visual representation of a person's lineage, tracing relationships to common ancestors. Visually similar to a chart, this diagram is usually presented in a tree structure starting with one individual as the root. 

A family tree is used around the globe with different purposes: A person would make a family tree to track down his or her origins to different countries or cultures, in sociology, to track down the ethnic predominance of the population, and mostly in medicine, where genetists, medics that researches human DNA, to track down different DNA-related diseases, in order to cure them.

from our parents and grandparents, to our children and grandchildren, every person in our family is related to us through DNA.