Summary
A trait controlled by many genes producing continuous variation, such as height and skin colour.
In depth
Many genes each add a small effect, so traits show a bell-shaped distribution. Environment (nutrition for height) adds more variation. Skin colour involves at least dozens of loci.
Such traits cannot be tracked by simple Mendelian ratios, and are analysed statistically.
Continuous traits such as height, weight, blood pressure and skin colour show normal distributions. Height is highly heritable (around 80 percent in well-nourished populations), but depends on thousands of variants each of tiny effect, so even the largest GWAS explain only part.
Nilsson-Ehle's wheat kernel colour experiment showed how two or three gene pairs, each adding red pigment, give a range of shades, with a 1:4:6:4:1 ratio for two genes. Environmental differences blur category boundaries, and the average of the parents often predicts a child's value (regression toward the mean).
Frequently asked questions
What is Polygenic Inheritance?
A trait controlled by many genes producing continuous variation, such as height and skin colour.
Which area of biology covers Polygenic Inheritance, and how advanced is it?
Polygenic Inheritance is one of the 54 topics in Genetics. It is rated Intermediate, so it suits learners who already know the core vocabulary. Related topics in this area include Heritability, Quantitative Trait Loci, Heredity.
Why does Polygenic Inheritance matter?
Polygenic risk scores combine many small effects to estimate risk of disease, but have limits for people far from the studied groups.
Can you give an example of Polygenic Inheritance?
Human height has over 12,000 associated genetic variants.
What should I learn before Polygenic Inheritance?
Work through the Beginner topics in Genetics first, such as Heredity, Gene, Allele, then return to Polygenic Inheritance. Intermediate topics assume the Beginner vocabulary.
What topics are related to Polygenic Inheritance?
The closest topics to Polygenic Inheritance are Heritability, Quantitative Trait Loci, Heredity, Genome-Wide Association Studies. Comparing them side by side is a good way to see how the ideas connect.
How can I check that I understand Polygenic Inheritance?
Read the summary and the in-depth section, then use the quick check on the interactive lesson for Polygenic Inheritance. To practise the whole of Genetics, use the Genetics quiz.
How is Polygenic Inheritance different from Heritability?
Polygenic Inheritance: A trait controlled by many genes producing continuous variation, such as height and skin colour. Heritability: The proportion of phenotypic variation in a population attributable to genetic differences. Read both side by side and note what each one explains.
How should I study Polygenic Inheritance step by step?
First, read the summary and write the definition in your own words. Second, read the in-depth section and note any example. Third, compare it with Heritability and explain the difference aloud. Finally, take the Genetics quiz and come back to this page for any question you miss.