Youve probably heard remarks like, She could drink me under the table or He is a total lightweight. Those comments, which come with (dubious) connotations of strength and weakness, are rooted in the concept of alcohol tolerance.

So what is alcohol tolerance? The term refers to the ability of some people to consume larger amounts of alcohol before feeling its effects than others, said Peter Martin, a professor of psychiatry and behavioral sciences at Vanderbilt University Medical Center.

There are several reasons why this happens, and thus why it seems like some people can drink endlessly without a buzz and others feel tipsy on half a glass of wine.

Gender, genetics and how much you drink all play a role in tolerance.