Why do height increases over generations if it is determined?

Question

by genes of parents??

Answer 1

I think that you might mean dominant instead of determined. Height is only partially determined by genes.  It appears that the environment is the key factor in the observed increasing human height.  As populations move from impoverished areas to areas with better living standards, successive generations increased in height.

Below is an example that is a copy and paste:

In the early 1970s, when anthropologist Barry Bogin first visited Guatemala, he observed that Mayan Indian men averaged only 157.5 cm (5 ft 2 in) in height and the women averaged 142.2 cm (4 ft 8 in). Bogin took another series of measurements after the Guatemalan Civil War had erupted, during which up to a million Guatemalans had fled to the United States. He discovered that Mayan refugees, who ranged from six to twelve years old, were significantly taller than their Guatemalan counterparts. By 2000, the American Maya were 10.24 cm (4 in) taller than the Guatemalan Maya of the same age, largely due to better nutrition and access to health care.

Answer 2

Well height is only influenced partially by genes, and partially by environment. Genes tell your body which proteins to make, but they can make more of those proteins if there are more nutrients available as building blocks.

Parents' genes will determine to some extent how tall a person will be, but they might get much taller using the same genes if they have better nutrition available than their parents. (Which is mostly the case with recent generations, since we tend to get more money and the ability to get more varied kinds of food than our parents' generations).

Answer 3

Height is determined by the DNA supplied by both of your parents, but this is only a starting point in making you who you are. Other factors in your life like a healthy diet, income, education, quality of your environment, exposure to cigarette smoke, and physical activity are just a few of the things that affect your development as you grow.

Answer 4

In a word, food.

Only recently have even more advanced societies

adequately fed most of their populations constantly.

Poor nutrition in the formative years stunts growth.

Maximum size may be an inherited characteristic,

but much of the population still doesn't reach it.