Our bodies produce an oily secretion called sebum to keep the skin waterproof and prevent it from drying out. People who have naturally oily skin tend to have larger pores. This is because when oil and dirt collect in their skin, this causes the pores to swell and grow bigger.
As you get older your skin loses its elasticity, which in turn can cause your pores to stretch and become even more prominent. Also, the older you are, the longer you have been exposed to the sun. The long-term effects of harmful uv rays will gradually damage the skin cells, and reduce the elasticity of the walls of the pore canals, thus causes the pores to swell and grow bigger.
Maintaining a regular and proper facial cleansing routine will help keep your pores clean and prevent problems like blackheads and acne from developing.
You might have a greater predisposition to having large pores if one or both of your parents have a similar condition. Generally, males tend to have larger pores than females. Hormonal changes in women, particularly during menstruation, might cause enlarged pores.