Review Question - QID 106550

A 30-year-old man presents to his primary care physician for a routine check-up. During the appointment, he remarks that he has started noticing some thinning and hair loss without other symptoms. The physician reassures him that he is likely experiencing male-pattern baldness and explains that the condition is largely inherited. Specifically he notes that there are multiple genes that are responsible for the condition so it is difficult to predict the timing and development of hair loss. What genetic principle is being illustrated by this scenario?