Not everyone has more flatulence or farting as they age but for some people they do tend to fart more and have more flatulence as they age.
Increased Flatulence as we age is usually caused by lactose intolerance which is a relatively common reason for more flatulence as we age.
Also some people as they get older develop small intestinal bacterial overgrowth which is another reason for increased gas build up in your intestines and an increase in flatulence.
It's normal for some people to have an increase in flatulence as they age and although it's embarrassing farting is a normal natural thing that everyone in the world does.