Most often, quantitative traits are subject to modifications — growth, weight, fecundity, etc. A classic example of modification variability is the variability of the shape of the leaves of an arrow leaf plant rooted under water. One specimen of the arrowhead has three types of leaves, depending on where the leaf develops: under water, on the surface or in the air. These differences in leaf shape are determined by the degree of their illumination, and the set of genes in the cells of each leaf is the same.
Various signs and properties of the body are characterized by a greater or lesser dependence on environmental conditions. For example, in humans, the color of the iris and blood group are determined only by the corresponding genes, and living conditions cannot affect these signs. But height, weight, physical endurance strongly depend on external conditions, for example, on the quality of food, physical activity, etc.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.