Skip main navigation

New lower prices! Get up to 50% off 1000s of courses. 

Explore courses

Understanding a pedigree

In this step you will be introduced to the meanings of the symbols and line connectors used to construct a family tree or pedigree
Doctors can use a pedigree to show how genetic disorders are inherited in a family. They can use this to work out the probability that someone in a family will inherit a condition.

In order to understand the following presentations on inheritance patterns, you may find it useful to spend a few moments looking at the images below and familiarising yourselves with the meanings of the symbols and connecting lines used to draw pedigrees.

We have also included a PDF version of the table in the downloads section below.

Please note: This table is best viewed in landscape mode when viewing this step on a mobile device.

Symbol Description / Meaning
Square Symbol Square / Male
Circle Symbol Circle / Female
Diamond Symbol Diamond / Gender unknown
Line Above Symbol Line above / Siblings
Angled Lines Above Symbol Angled lines above / Twins
Line Between Symbol Line between / Partners
Two Lines Between Symbol Two lines between / Consanguineous (blood related) couple
Line Down Symbol Line down / Children
Shaded Symbol Shaded / Affected individual
Shaded Dot Symbol A small circle inside a larger circle or square / Carrier
Line Diagonally Through Symbol Line diagonally through symbol / Individual is deceased

Just for fun

Try drawing your own family pedigree. If you can, go back three generations (including your own).

Is your family pedigree straightforward or, like many families, more complex and challenging to draw?

© St George’s, University of London
This article is from the free online

The Genomics Era: the Future of Genetics in Medicine

Created by
FutureLearn - Learning For Life

Reach your personal and professional goals

Unlock access to hundreds of expert online courses and degrees from top universities and educators to gain accredited qualifications and professional CV-building certificates.

Join over 18 million learners to launch, switch or build upon your career, all at your own pace, across a wide range of topic areas.

Start Learning now