Parents with blond hair: what hair colour will the baby have?
Blond hair is the most likely, at 97%. The full odds, with no red hair in either family: blond 97% and red 3%. In this simple model, black or brown hair is not possible.
Red hair anywhere in the family raises the chance of red: the table further down shows by how much.
Most likely hair colour
Blond
“Unlikely” means 0% in this simple model. Hair colour depends on many genes, so it can still happen.
Hair often darkens through childhood: a blond toddler can be brown-haired by their teens, and a baby's first hair often falls out and grows back a different shade.
Estimate from a two-gene model: one gene for dark or light pigment, and MC1R for red.
A simplified estimate for fun. Real genetics is more complex.
How we work it out
The model uses two genes: one for dark or light pigment, where dark wins, and MC1R, where red only shows when a child gets the red version from both parents. Here, dark means black or brown: the model treats them alike.
If red hair runs in the family
A parent without red hair can carry the red version of MC1R without knowing it. That is more likely when a close relative has red hair.
| Red hair in the family | Black or brown | Blond | Red |
|---|---|---|---|
| Neither family | 0% | 97% | 3% |
| One family | 0% | 96% | 4% |
| Both families | 0% | 94% | 6% |
Frequently asked questions
Can parents with blond hair have a baby with black or brown hair?
Not in this simple model. Hair colour depends on many genes, so it can still happen, but rarely.
Can parents with blond hair have a baby with blond hair?
Yes: 97% of the time when there is no red hair in either family.
Can parents with blond hair have a baby with red hair?
Yes: 3% of the time when there is no red hair in either family.
- MedlinePlus Genetics (US National Library of Medicine): Is hair color determined by genetics?
- Valverde P et al. Variants of the melanocyte-stimulating hormone receptor gene are associated with red hair and fair skin in humans. Nature Genetics 1995;11:328-330
- The Tech Interactive, Ask a Geneticist: What are the chances my child will have red hair and blue eyes?
- Morgan MD et al. Genome-wide study of hair colour in UK Biobank explains most of the SNP heritability. Nature Communications 2018;9:5271