Here are three things you probably didn’t know about deodorant:

1. You’re supposed to put antiperspirant on at night. It works best if it has time to soak into your sweat ducts. If you put it on right after you take a shower in the morning, you immediately start sweating it off.

2. We’re still not sure what causes yellow pit-stains. Researchers think the aluminum in antiperspirant turns your shirt yellow when it reacts with something, but they don’t know if it’s your sweat, your skin, your detergent, or the actual fabric.

3. You might not even need deodorant. Some people just don’t have B.O., and it has to do with genetics. There’s a specific gene called ABCC-11. If you don’t have it, you probably don’t need deodorant.

There’s an easy way to tell if you have it or not, but it’s kind of gross — you have to look at your earwax. If it’s dry and flaky, you probably don’t have the gene, and don’t need deodorant. If it’s dark and sticky, you probably DO.

For some reason, a lot of Asian people don’t have it, but if your ancestors were from Europe, there’s about a 98 percent chance you do.