Using a double-line symbol denotes consanguineous (related by blood ) marriages on a pedigree chart. The single horizontal lines connecting a square and circle show that a pair has mated and the vertical lines connecting a pair to other squares or circles are the offspring. A square represents a male and a circle is the symbol for a female.
Pedigree charts show how characteristics are passed from one generation to the next and serve as a guide to help enhance desirable traits in the next generation. They can also be used in genetic research, as well as, to isolate diseases in clinical settings. They are practical for humans, show dogs and race horses and are needed to prove bloodlines.