Sex-Linked Inheritance Calculator

X-linked traits like color blindness and hemophilia are inherited differently by sons and daughters because they're carried on the X chromosome — the Sex-Linked Inheritance Calculator shows you the probability breakdown for any such trait. Select the Mother's Genotype (Normal, Carrier, or Affected) and the Father's Genotype (Normal or Affected), then optionally enter a Trait Name to get the percentage of Affected Males, Affected Females, Carrier Females, Normal Males, and Normal Females expected among offspring.

Select the mother's X chromosome genotype

Select the father's X and Y chromosome genotype

Name of the X-linked trait being analyzed

Results

Affected Males

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Affected Females

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Carrier Females

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Normal Males

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Normal Females

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Results Table

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Frequently Asked Questions

What is X-linked inheritance?

X-linked inheritance is a pattern where genes located on the X chromosome are passed from parents to offspring. Since males have only one X chromosome (XY), they need only one copy of a recessive allele to express the trait, while females need two copies (XX).

Why are males more likely to be affected by X-linked recessive traits?

Males are more likely to be affected because they have only one X chromosome. If they inherit the recessive allele, they will express the trait. Females have two X chromosomes, so they need to inherit the recessive allele from both parents to be affected.

What does it mean to be a carrier female?

A carrier female has one normal allele (X⁺) and one affected allele (Xᵃ). She typically doesn't express the trait but can pass the affected allele to her offspring. About 50% of her sons may be affected, and 50% of her daughters may be carriers.

Can fathers pass X-linked traits to their sons?

No, fathers cannot pass X-linked traits to their sons because fathers give their Y chromosome to sons, not their X chromosome. Fathers pass their X chromosome only to daughters.

What are common examples of X-linked recessive traits?

Common X-linked recessive traits include color blindness (red-green), hemophilia A and B, Duchenne muscular dystrophy, and some forms of intellectual disability. These conditions are much more common in males than females.

How accurate are Punnett square predictions?

Punnett squares show theoretical probabilities based on genetic principles. Actual outcomes in small families may vary due to chance, but the predictions become more accurate when looking at large populations or many offspring.

Can two normal parents have an affected child for X-linked traits?

Yes, if the mother is a carrier (X⁺Xᵃ) and the father is normal (X⁺Y), they can have affected sons (25% chance) even though both parents appear normal. The mother carries the recessive allele without expressing it.