Enter both parents' traits to compare what trait probabilities each of your two children inherited. Understand why siblings from the same parents often look completely different.
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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.
Full siblings share on average only 50% of their DNA. The other 50% differs due to independent assortment during meiosis — which is why siblings can have dramatically different eye color, hair texture, or height despite having the same parents.
During human reproduction, egg and sperm cells are formed through meiosis. This process randomly splits a parent's double-stranded DNA into single strands. Because of independent assortment and crossing-over, every single egg and sperm contains a unique, random combination of genes.
Even though siblings get their genes from the same pool, the random selection of 50% of the parent's genes means the exact combinations vary wildly.
Chromosomes align and separate randomly during cell division, meaning siblings get a completely different shuffle of maternal and paternal chromosomes.
For traits controlled by many genes (like height and skin tone), the multiple genes act like a genetic lottery, causing siblings to fall on different points of a spectrum.
50% is a statistical average. A sibling could share slightly more or less DNA with their brother or sister, and which specific genes they share is completely random.
Yes. If both parents carry a recessive blue eye gene, one child can inherit blue eyes while their sibling inherits brown eyes.
Hair texture is an incomplete dominant trait. If parents carry different variants, one sibling might inherit curly, one wavy, and one straight hair.
Yes, identical twins come from the same fertilized egg and share 100% of their genetic code, whereas fraternal twins share 50% just like regular siblings.
No. Each pregnancy is an independent event. The genetic lottery resets, and birth order has absolutely no influence on which genes are passed down.