How hair color is inherited
Hair color is not decided by one dominant gene. Large genetic studies link it to hundreds of variants that each nudge pigment up or down, producing a continuum from blonde through light and dark brown to black. A child's hair usually lands near the parents' average, with spread on both sides and a pull toward the most common shades. Red hair works differently: it mostly comes from two variants of the MC1R gene, which switch pigment from dark eumelanin to red pheomelanin.
Why this isn't a Punnett square
A Punnett square treats dark hair as simply dominant over light. That model can't explain why two light-brown parents often have a blonde child, or why only some people with two MC1R variants are redheads. This calculator uses a polygenic model for the dark–light continuum and a separate MC1R model for red, both anchored to the hair-color mix of more than 340,000 people in UK Biobank.
Baby hair color chart by parent combination
| Mom \ Dad | Black | Dark brown | Light brown | Blonde | Red |
|---|
| Black | Black 58% | Dark brown 60% | Dark brown 64% | Dark brown 48% | Dark brown 54% |
| Dark brown | Dark brown 60% | Dark brown 63% | Dark brown 45% | Light brown 58% | Dark brown 38% |
| Light brown | Dark brown 64% | Dark brown 45% | Light brown 58% | Light brown 51% | Light brown 48% |
| Blonde | Dark brown 48% | Light brown 58% | Light brown 51% | Blonde 64% | Light brown 43% |
| Red | Dark brown 54% | Dark brown 38% | Light brown 48% | Light brown 43% | Red 67% |
Each cell shows the single most likely adult color; the calculator above shows the full spread.
How the numbers are calculated
- Population shares come from UK Biobank: red 4.6%, blonde 11.5%, light brown 41.1%, dark brown 37.2%, black 4.2%.
- Dark–light hair is modeled as a heritable continuous trait (heritability 0.9); children are predicted from the average of both parents.
- Red hair uses the finding that 92% of redheads carry two MC1R variants; the chance a non-red parent carries one is set so that families without red hair produce about 4% redheads, near the population rate.
- How much red hair in the family raises the odds, and how grandparents are weighted, are our own estimates, because studies don't report them directly.
Hair and eyes are inherited separately, so check the baby eye color calculator too: a blonde baby can still have brown eyes. For the rest of the picture, the child height predictor estimates adult height from both parents, and the twins calculator gives your chances of twins.
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See what my baby will look like →Questions parents ask
What hair color will my baby have?
Most children end up close to the average of their parents' hair colors, with some spread either way. Darker hair is more common when either parent has dark hair, but blonde and red can appear when both parents carry hidden variants.
Can two dark-haired parents have a blonde baby?
Yes, though it is uncommon. Hair color depends on hundreds of genetic variants, so two brown-haired parents can pass on mostly "light" variants by chance. Many blond toddlers of dark-haired parents also darken by school age.
Will my baby have red hair?
Red hair mostly comes from inheriting two variants of the MC1R gene, one from each parent. Parents without red hair can both carry one, and red hair can skip generations. Even with two variants, many people end up blonde or light brown because other genes modify the effect.
When does a baby’s hair color settle?
Newborn hair often falls out and grows back a different shade. Hair commonly darkens through childhood, so this calculator predicts adult hair color rather than baby hair.
Why does adding grandparents help?
A parent can carry variants they don't show, such as for red or blonde hair. Grandparents' hair colors hint at those hidden variants, so they shift the estimate.
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