Multifactorial inheritance: The type of hereditary pattern seen when there is more than one genetic factor involved and, sometimes, when there are also environmental factors participating in the causation of a condition.
Many common traits are multifactorial. Skin color, for example, is multifactorially determined. So is height and so also is intelligence.
The most common diseases tend also to multifactorial. Type 2 diabetes, the most common type of diabetes, is multifactorial. It is due to the inheritance of susceptibility genes (genes that make one susceptible to developing diabetes) plus environmental factors such as obesity. Obesity, in turn, clearly is multifactorial in causation.