The height a person reaches as an adult depends on the genes they inherit from their parents as well as general health and nutrition during their years of growth. The child of short parents is more likely to be short themselves than the child of tall parents. There is a lot of variation; brothers or sisters with the same parents will not all end up the same height and parents can, by chance, have a child who is unexpectedly tall or short in relation to the rest of the family.
Illnesses or poor nutrition during childhood or being small or premature at birth may mean children do not reach their full potential adult height. The average height of the population has gradually increased over the centuries because children have been better nourished and have had fewer illnesses and infections.
