No Hangover? Not Good:

While there is nothing fun about a hangover, you should be concerned if you have the ability to consume large quantities of alcohol with little or no adverse effects. Research shows that individuals who don’t experience hangovers after heavy drinking may be inclined to drink more heavily over time, possibly taxing an unsuspecting susceptibility to alcoholism , and thereby incurring the illness. Many studies have shown this biologic response to alcohol to be inherited. Talk to the EAP to learn more.

Source: Nature (Vol. 436, p 845).