Select any trait type and enter each parent's phenotype. The calculator applies Mendelian inheritance models to show dominant and recessive outcome probabilities across all genotype combinations.
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Generated at traitgen.com, Free genetics education. Not medical advice.
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⚠️ Educational only. Probability estimates based on genetic models, not medical advice.
Gregor Mendel discovered dominant and recessive inheritance in 1866 by cross-breeding pea plants. He noticed certain traits disappeared in one generation and reappeared in the next — exactly what recessive inheritance explains.
Genetic inheritance follows Mendelian rules for single-gene traits. Every individual inherits two alleles for each gene (one from each parent). A dominant allele overrides the recessive allele when both are present, meaning the recessive trait is only expressed when an individual inherits two copies of the recessive variant.
Dominant traits only require one copy of the allele (e.g., A) to be expressed in the physical appearance (phenotype). A heterozygous individual (Aa) will display the dominant trait, while the recessive allele remains hidden.
Recessive traits require two copies of the allele (e.g., aa) to be expressed. A person can carry a recessive gene for generations without knowing it, until they have a child with another carrier.
A grid system used to predict the genotypes of offspring from parents of known genotypes. It represents every possible combination of maternal and paternal alleles.
A carrier has a heterozygous genotype (Aa) and can pass the recessive allele to offspring but does not show the trait themselves. An expresser has the physical trait expressed.
No, dominant traits cannot skip generations because they require at least one parent to express the trait. If a child has a dominant trait, at least one biological parent must also have it (barring rare mutations).
A carrier is an individual who has inherited a recessive allele for a trait but does not display it because they also have a dominant allele. They can pass the recessive allele to their children.
If both parents are heterozygous carriers (Aa), there is a 25% chance their child will inherit the recessive allele (a) from both parents, resulting in the recessive genotype (aa) and phenotype.
No. In genetics, 'dominant' only refers to the relationship between alleles and how they are expressed. Many rare genetic diseases are dominant, and some dominant traits are less common in the population than recessive ones.