In the future, aliens who have invaded earth are conducting a survey of teenagers. When examining body modifications, they conclude that piercing is a polygenic trait. They reached this conclusion by examining only the number of piercings in a teenager, and the number of piercings in their parents. Why might they conclude that the propensity for piercings is a polygenic trait? Explain your answer fully in words, no equations please, including all observational patterns that might have led the aliens to their conclusions.
Polygenic traits are the result of the interaction of several genes leading to an observed phenotype. In this case, the observation that the aliens made of piercings in teenagers.
For example, a phenotype like high blood pressure is not the result of a single gene for high BP. The phenotype is an interaction between several genes that control factors like weight, cholesterol level, kidney function (salt transporter genes), smoking/addiction, ...
This question puts into practise the concept of polygenic traits. The solution explains how observations are made and a conclusion is reached. As well, the solution explains the concepts behind reaching the conclusion.