So, men growing grumpier as they age is not a right of passage, as many affected by it have inappropriately assumed for centuries.

There actually may be a medical explanation to substantiate why men morph to grouchy guys as they age. It is possible that grouchiness and aging in men can be traced to a reduction in testosterone level, according to a report by NBC News.

Grumpiness is even used as a mood description in screening questionnaires for low testosterone. One form many U.S. male patients are asked to fill out is a test for Androgen Deficiency in Aging Men (ADAM). Androgen is the family of hormones that controls the development of masculine traits. Question No. 6 on that form reads: “Are you sad and/or grumpy?”