Reflux is extremely common in premature babies, children with asthma, cystic fibrosis, muscular or neurological problems and conditions such as Down Syndrome. There are probably several different causes of reflux. Genetics seems to be a key factor in some families but it can also be caused by allergies and intolerances, many different neurological problems that make it hard for the muscles to work properly, or a really bad diet. Some medications can cause reflux. Many people with other digestive disorders such as slow intestinal movement or intolerance to wheat have reflux.
Reflux can be very obvious or pretty subtle.
You can often spot a baby with reflux by the fact that they spit up constantly and their mothers look like they are ready to collapse. Reflux in teens, however is often diagnosed by a doctor who is very familiar with reflux and has taken a very thorough history. Reflux may first be suspected by a neighbor who is familiar with reflux symptoms or you may have to go to several different doctors until one finally sees the pattern that explains everything. There is no perfect test for reflux. Testing may not even be necessary to diagnose reflux - it can be diagnosed based on asking lots of questions.