Most people who have murmers are born with them. Some are called innocent murmers that can be heard but don't hurt anything. Others occure when the blood that is in the chambers of the heart is pumped out and the valves that regulate this stay open or closed a little longer than they are supposed to. Or the valve could be deformed in someway. If your lips or hands are blue that might be a good sign that your blood return is not good. Some murmers require surgery to fix or replace the valve but most are harmless. Although you will need to take antibiotics before dental appts. Or anything where bacteria could enter the bloodstream this could cause an infection as it passes through the heart by sticking to a valve that say doesn't open all the way sort of like a clogged drain. I've had one for 39 years and i'm still ticking...