Dry skin is often genetic. It is caused by the skin not producing enough of the two essential lipids it needs to function. These lipids are sebum (oil) and epidermal lipids.
If these lipids are not produced in sufficient volumes, then the health of the skin is affected. The skin will not be able to shed effectively, and this will lead to a compromised barrier function. This means that irritants could penetrate the skin and result in inflammation, stinging, burning and even milia (tiny white bumps on the skin). As well as appearing flaky and dry, if you suffer from this condition, your skin may feel tight and reactive.
Dry skin ages prematurely as it has a slower cell reproduction, poor functioning and requires daily protection from the environment.