Mark Leyner and Dr. Billy Goldberg explained the answer in their book, "Why Do Men Have Nipples?”.
"Asparagus contains a sulfur compound called mercaptan. It is also found in onions, garlic, rotten eggs, and in the secretions of skunks," they wrote. "The signature smell occurs when this substance is broken down in your digestive system. Not all people have the gene for the enzyme that breaks down mercaptan, so some of you can eat all the asparagus you want without stinking up the place. One study published in the British Journal of Clinical Pharmacology found that only 46 percent of British people tested produced the odor while 100 percent of French people tested did."
To read a short excerpt from Leyner and Goldberg's book, click here.
allDAY - Answers from TODAY: Why does asparagus make your urine smell?