Polygenic inheritance and environmental effects
How is height inherited?
- Continuous variation. Unlike Mendel's pea plants, humans don’t come in two clear-cut “tall” and “short” varieties. In fact, they don't even come in four heights, or eight, or sixteen. Instead, it’s possible to get humans of many different heights, and height can vary in increments of inches or fractions of inches.Histogram showing height in inches of male high school seniors in a sample group. The histogram is roughly bell-shaped, with just a few individuals at the tails (60 inches and 77 inches) and many individuals in the middle, around 69 inches.
- A complex inheritance pattern. You may have noticed that tall parents can have a short child, short parents can have a tall child, and two parents of different heights may or may not have a child in the middle. Also, siblings with the same two parents may have a range of heights, ones that don't fall into distinct categories.