A heritability of body weight of 0.4 indicates that 40% of body weight is influenced by genetic factors, while 60% is influenced by environmental factors. Although genetics play a role in individual tendencies towards being lean or not, environmental factors and diet significantly impact body weight. Overall, both genetic and environmental factors contribute to the diverse shapes and sizes of individuals.

1. A heritability of body weight of 0.4 means that body weight is determined for 40% by genetic
factors and for 60% by environmental factors. True or false?
Solution
True. This is not to say that there are no genetic factors influencing body weight, different people
will have different tendencies, to be lean, or not so lean, etc. just like height and other physical
features are determined by many gene variants. Even the microbiome is influenced by both
genetic factors that favor some gut bacteria over other, but diet plays a huge role too. People do
come in all shapes and sizes, but the environment plays a huge role.