How to
How to make a pedigree chart
A pedigree chart follows one trait or genetic condition through a family. Every person is a symbol, generations sit in rows from the oldest at the top, and lines join couples and their children. Genetics students use pedigrees to decide whether a trait is dominant or recessive and whether it sits on the X chromosome.
The symbols
- Square for a male, circle for a female, diamond when the sex is not known or not stated.
- Filled symbol for someone who has the trait or condition (affected).
- Half filled or a dot in the center for a carrier: one copy of a recessive allele and no signs of the condition. Choose the style your textbook uses.
- Diagonal line through the symbol for someone who has died.
- Arrow with a P for the proband, the person through whom the family came to attention.
- Horizontal line between two symbols for a couple, a double line when the partners are related by blood.
- Roman numerals mark the generations, and people are numbered left to right in each one, so II-3 means the third person in the second generation.
- Give everyone an ID. Numbers work well. Type the sex as M, F or leave it blank for unknown.
- Link children to parents. For each child, enter the father's ID and the mother's ID. Couples with children are found from that alone.
- Add partners without children. Put the partner's ID in Partner ID so the couple line is drawn.
- Mark the status. Type affected, carrier, deceased or proband in Status, several at once separated by commas.
- Export. Download a PNG for a worksheet or slides, or an SVG for print, or copy a link to share the family.
Reading a pedigree
Look for three clues. If affected children have two unaffected parents, the trait is probably recessive. If every affected person has an affected parent and the trait shows in each generation, it is probably dominant. If it mostly affects males and passes through unaffected carrier mothers, suspect X-linked inheritance. To check a guess, work out the genotypes of the parents and test the cross with the Punnett square calculator.
Tip
The sample opens with a recessive trait: two carrier parents in generation II have an affected son, the proband. Change a status and the chart redraws, which makes it a quick way to build practice problems.
Pedigree or genogram?
A pedigree tracks inheritance. A genogram uses similar symbols to show relationships in a family, such as marriages, divorces and people living together, and is used in social work and family therapy.
Questions people ask
How to make your own pedigree chart?
Number every family member, write down their sex and, for each child, the numbers of the father and mother. Mark who has the trait, who carries it and who has died. Enter that list in the table above: the generations, couple lines and sibling lines are drawn for you with the standard symbols, ready to download.
What is the difference between a pedigree chart and a family tree?
A family tree records who is related to whom, usually with names and dates. A pedigree chart uses a fixed set of symbols to follow one trait or condition through the family: squares for males, circles for females, filled shapes for affected people. Genetics classes and genetic counselors use pedigrees to work out how a trait is inherited.
How to create a pedigree chart in Word?
Word has no pedigree tool, so people draw squares, circles and connectors with Insert, Shapes and line them up by hand, which is slow to fix when a relative is added. Building the chart here and inserting the downloaded PNG, or the SVG for sharp printing, is quicker, and you can edit the family and export again.
Who made the pedigree chart?
No single person invented it; family diagrams are centuries old. The symbols used in medical genetics today come from the National Society of Genetic Counselors, whose task force, led by Robin Bennett, published standard pedigree nomenclature in 1995 and has updated it since. This maker follows those common symbols for sex, affected status, carriers, deaths and the proband.
Is there a truly free family tree maker?
For a pedigree or a small family diagram, yes: this maker is free, has no sign-up and no watermark, and runs in your browser, so family details are not uploaded. It is not genealogy software, so there are no record searches or huge databases; for a family history project with hundreds of people, a dedicated genealogy program suits better.