What is autosomal dominant inheritance?

In autosomal dominant inheritance, a single copy of the variant allele (on a non-sex chromosome) is sufficient to cause the trait. An affected individual is typically heterozygous (Aa); two copies (AA) are usually lethal or very rare. Unaffected individuals are homozygous recessive (aa).

What is autosomal recessive inheritance?

Autosomal recessive traits require two copies of the variant allele (aa) to be expressed. Individuals with one copy (Aa) are carriers — they do not show the trait but can pass the allele to offspring. When two carriers mate, each child has a 25% chance of being affected.

How does X-linked recessive inheritance differ?

X-linked recessive genes sit on the X chromosome. Males (XY) are affected if they inherit one copy of the variant X allele because they have no second X to mask it. Females (XX) are usually carriers with two X chromosomes; they are affected only if both X chromosomes carry the variant allele.

What does "carrier" mean in this tool?

A carrier is a heterozygous individual (one normal + one variant allele) who does not show the trait but can transmit the variant allele to children. The term is most commonly used for autosomal recessive and X-linked recessive traits.

Why are some parent genotype combinations unavailable?

The available genotypes depend on the inheritance mode. For autosomal dominant, homozygous affected (AA) is excluded because it is typically lethal or not clinically relevant. For X-linked traits, male options are limited to X^A Y (unaffected) or X^a Y (affected) because males are hemizygous.

Does this tool handle incomplete dominance or codominance?

No. This calculator models complete dominance only: one dominant allele fully masks the recessive allele. For incomplete dominance, codominance, or polygenic inheritance, a different model is required.

How do I use this tool to solve pedigree chart problems?

Use your pedigree chart to deduce each parent's genotype first (such as identifying obligate heterozygous carriers from affected offspring or parents). Then select the inheritance pattern and deduced parent genotypes in the calculator to compute offspring phenotype probabilities.

Pedigree Probability Calculator

Select an inheritance pattern, choose parent genotypes, and instantly see offspring probabilities in a color-coded Punnett square.

Inheritance Settings

Inheritance Pattern

Parent 1 (Mother)

Parent 2 (Father)

Select an inheritance pattern and parent genotypes on the left.

Cross

Punnett Square

Offspring Probabilities

Summary

The Pedigree Probability Calculator applies Mendel's laws of segregation to calculate single-cross offspring genotype and phenotype probabilities from parent genotypes deduced from a pedigree. Choose the inheritance mode (autosomal dominant, autosomal recessive, or X-linked recessive) and parent genotypes to view a Punnett square alongside offspring probability percentages. All computation runs locally in your browser — no data is sent to any server.

How it works

Select the inheritance pattern: autosomal dominant, autosomal recessive, or X-linked recessive.
Choose the genotype for Parent 1 from the available options (e.g., affected heterozygous, carrier, unaffected).
Choose the genotype for Parent 2 in the same way.
The tool builds the Punnett square by crossing every gamete combination from both parents.
Each offspring cell is classified by phenotype: affected, carrier, or unaffected.
Probability percentages are displayed for each phenotype class with color-coded bars.

Use cases

Estimate the chance that a child inherits a recessive disorder when both parents are carriers.
Determine offspring risk when one parent has an autosomal dominant condition.
Calculate X-linked recessive transmission probabilities for conditions such as hemophilia.
Support genetic counseling study and exam preparation.
Illustrate inheritance patterns in biology or genetics classroom lessons.
Quickly verify hand-calculated pedigree probabilities for homework assignments.
Model carrier detection scenarios for family planning decisions.
Explore how inheritance mode changes offspring ratios for the same cross.

Frequently Asked Questions

Last updated: 2026-09-30 · Reviewed by Nham Vu