Pedigree charts for inheritance problems, with genotypes
Pedigree draws a family’s pedigree chart with the standard symbols: squares for males, circles for females, filled in when affected, with generation numerals down the left and a number under each person. Pick an inheritance mode (autosomal dominant, autosomal recessive, X-linked recessive, X-linked dominant or Y-linked) and it draws a random family whose genes are passed down by Mendel’s rules, looking for one in which every other mode is ruled out or far less likely, so students can work out which it is. Or start from a classic family for hemophilia, Huntington’s disease, cystic fibrosis, albinism, red–green color blindness or vitamin D–resistant rickets.
Click anyone in the pedigree to change them, or add a child, partner or sibling. As you go, the generator checks the family against every mode, names the clue that rules each one out (such as unaffected parents with an affected child), and warns you when a change makes the family impossible for the mode you picked. Teachers use it for genetics tests and worksheets: show genotypes under each person for the key or blank lines for students, and turn on the answer key line to print the inheritance mode under the figure.
What you can set
- Inheritance: autosomal dominant, autosomal recessive, X-linked recessive, X-linked dominant or Y-linked
- A random family of 2, 3 or 4 generations, small, medium or large, with New pedigree for another one
- Or a classic family: hemophilia in a royal family, Huntington’s disease, cystic fibrosis, albinism, red–green color blindness or vitamin D–resistant rickets
- Anyone’s sex (male, female or unknown) and status (unaffected, carrier or affected), deceased and proband marks, twins and related partners, and children, partners and siblings added or removed
- Carriers: hidden, half filled or a center dot
- Genotypes under each person, worked out from the pedigree or left as blank lines, with the allele letter you choose
- Generation numerals, individual numbers and the key, each on or off
- A chart title, and an answer key line naming the inheritance mode
Copying, printing and sharing
Copy the figure straight into a test, worksheet or slide, or download it as a PNG or SVG. Printing the page prints
just the figure. Share link copies the page’s address with your settings in it, so anyone who opens it sees this
exact figure, and presets save settings you use often in your browser. It’s free, with no sign-up.
Frequently asked questions
How do you tell if a pedigree is dominant or recessive?
Look for two parents with the same phenotype and a child who differs. If two unaffected parents have an affected child, the trait is recessive: both parents must carry the allele without showing it. If two affected parents have an unaffected child, it is dominant. A dominant trait usually shows in every generation, each affected person having an affected parent, while a recessive trait often skips generations.
How can you tell if a trait is X-linked from a pedigree?
An X-linked recessive trait affects mostly males and usually passes from an affected man through his daughters, who are carriers, to some of their sons. An affected man never passes it to his sons, who get his Y. It is ruled out when an affected daughter has an unaffected father, or an affected mother has an unaffected son. An X-linked dominant trait passes from an affected father to all of his daughters and none of his sons.
What does a Y-linked pedigree look like?
Only males are affected, and every son of an affected man is affected, so the trait runs straight down the male line from father to son. Women never have it and never pass it on, and an unaffected man never has an affected son. One affected woman, or an affected son of an unaffected father, rules Y-linked inheritance out.
What do the symbols in a pedigree chart mean?
A square is a male, a circle a female and a diamond a person of unknown sex. A filled symbol is affected; a half-filled one, or one with a dot in the middle, is a carrier. A slash marks someone who has died, and an arrow marks the proband, the person the family came to attention through. A line joins partners (a double line when they are related), and their children hang from the line below in birth order. Generations are numbered I, II, III down the left and people 1, 2, 3 from left to right, so II-3 is the third person in generation II.
Why do some genotypes have a blank, like A_?
Often a pedigree can’t tell whether someone has one copy of an allele or two: an unaffected person in a recessive pedigree may be a carrier, and an affected person in a dominant one may be homozygous. When Genotypes is set to Answers, the generator writes the allele it can be sure of and a blank for the other, as students would. For a recessive trait, showing carriers settles it, because an unshaded symbol then means the person is not a carrier.
Can I make a pedigree worksheet with blank genotypes?
Yes. Under Labels, set Genotypes to Blanks to put a line under every person for students to fill in, and leave carriers hidden so they have to work them out. Switch Genotypes to Answers, and turn on the answer key line under Chart title, to print the key for the same family.
Are my changes to the family saved?
Yes. A family you change by hand is written into the page address, so a copied link or a saved preset brings back exactly that family. Changing the inheritance mode keeps it; New pedigree, or a different number of generations or family size, starts a new random family.
Biology Figures Pedigree