Final answer:
Quantitative traits in genetics are not controlled by a single pair of genes and can be influenced by environmental factors. They are polygenic and show continuous variation.
Step-by-step explanation:
Quantitative traits in genetics are traits that are controlled by multiple genes and show continuous variation. One thing that is not true of quantitative traits is that they are controlled by a single pair of genes, like Mendelian traits. Instead, quantitative traits are polygenic, meaning they are controlled by multiple genes.
For example, height is a quantitative trait that is controlled by multiple genes. It is not determined by a single pair of genes, but rather by the combined effect of many genes. This is why there is a wide range of heights in a population.
Another thing that is not true of quantitative traits is that they are not affected by environmental factors. In fact, environmental factors, such as nutrition and exercise, can have an impact on the expression of quantitative traits. For example, a person's height can be influenced by their diet and overall health.