Hair type and texture are complex traits that are influenced by genetics as well as other factors. While hereditary factors play an important role, the answer to whether hair is inherited specifically from mother or father is more nuanced.
Genetics of hair
Human hair texture and color are polygenic traits, meaning they are influenced by multiple genes. Specific genes that impact hair include:
- EDAR gene – associated with straight vs curly hair
- PAX3 gene – influences red hair
- MC1R gene – also influences red hair
- SCRC gene – impacts hair curliness
In addition, there are over 100 genetic loci that can affect hair texture and growth patterns. The inheritance patterns of these hair genes are complex.
Contributions from mother and father
Each parent contributes half of their genes to their offspring. This means that hair traits are inherited from both sides of the family. However, some key points about maternal and paternal contributions include:
- Mitochondrial DNA is passed from mother to child. Mitochondrial genes impact hair growth and quality.
- The genes contributed by each parent can interact in ways that are not always predictable based on the parents’ hair.
- Certain traits like hairline shape and balding patterns are sometimes more associated with fathers.
- Maternal grandfather balding can also hint at male pattern baldness risk.
Overall, hair traits depend on the particular combination of genes inherited. While genes from both parents influence hair, some genetic factors are maternally inherited.
Other determinants of hair texture
Genetics are not the only influence on hair characteristics. Other factors that affect hair include:
- Age
- Health and nutritional status
- Hormones
- Hair products and damage from treatments
- Environmental factors like sun exposure
Lifestyle, diet, and hair care habits can alter the hair in significant ways from the genetic baseline. Hair texture and curl patterns may change over the course of a person’s life.
Racial and ethnic differences
Certain hair traits like curliness, thickness and volume show patterns across racial and ethnic groups. However, there is a range of hair types within populations. General distributions of hair types by ancestral background include:
| Ancestral group | Typical hair types |
|---|---|
| African | Very curly and coiled; dense and voluminous |
| Asian | Straight and thick |
| Caucasian | Straight, wavy or curly; medium-textured |
| Hispanic/Latin American | Straight, wavy or curly; varies from fine to coarse |
These differences in hair morphology across broad ethnic groups reflect underlying genetic differences. However, there is extensive overlap in hair types across populations due to genetic variations.
Family patterns
Examining the hair traits across close family members can provide hints about genetic inheritance. Some patterns to look for include:
- Similar hair color and texture among siblings
- Daughters’ hair resembling mothers’ hair
- Fathers’ and sons’ hair or hair loss patterns correlating
- Grandparent-grandchild resemblance in hair type or balding
These familial patterns provide evidence of inherited hair traits. However, even within families, there is variation in hair texture and curliness among siblings and across generations. Environmental effects and gene interactions make hair traits complex and unpredictable.
Genetic testing
Genetic testing is available to provide information about ancestry and insights into hair. Three types of genetic tests that can be useful are:
- Ancestry DNA tests – Analyze ancestral markers and provide estimates of ethnic heritage. Can explain patterns of hair traits across racial backgrounds.
- Hair trait DNA tests – Analyze specific hair gene variants that affect curliness, thickness, balding risk and more. Useful for predicting hair traits.
- Mitochondrial DNA tests – Trace maternal lineage via mtDNA. Provides insights about maternal influence on hair.
While genetic testing provides useful hereditary information, environmental influences can still modify hair from genetic expectations. Ongoing research continues to uncover new genetic factors that shape hair morphology and growth.
Conclusions
- Hair traits like texture, curl pattern, thickness and growth are polygenic, influenced by many genes.
- Genes contributed by both parents interact to influence hair phenotype.
- Some hair genetic factors are maternally inherited in the mitochondrial DNA.
- Non-genetic factors like age, health, and environmental exposures also affect hair characteristics.
- Genetic testing can provide clues about ancestry and inherited tendencies for hair traits.
- Hair morphology results from a complex interplay of maternal genetics, paternal genetics and non-hereditary factors.
While genes from both parents play a role, mothers contribute specific hair gene variants and mitochondrial DNA that can strongly influence hair traits. Ultimately, the inheritance of hair characteristics is multifactorial with contributions from both maternal and paternal lines.
