Laziness is caused by low energy, which can be due to lack of eating and exercising to psych up the body muscles. Laziness can also be due to poor planning, which leads to lack of motivation and long-term vision. Once you have placed your planed schedule, you will keep up to it, thus you will not feel lazy.
Laziness is often times an inherited trait, as is many others such as racism, eating habits, poor hygiene etc. As a child you more often than not, learn from your surroundings. It is up to the person to break those bad habits. Nobody can or will do it for them.