“Just reach for it. The hold is right in front of you!” says my climbing partner in Joshua Tree, California, on another fabulous day on the rock.

He means well, but men often give women unsolicited “beta,” even if we climb at their level or better. I’ve almost never seen the same men give male climbers advice.

“I told you, I can’t!” I bark back, frustrated that he doesn’t believe me.

“Just reach! It’s right there! You’re making this harder than it is!”

“Dude, I’m like seven inches shorter than you. I literally can’t reach it, OK?!”

The first time I understood that men are the default gender and women have to mold ourselves to fit into a world made for them (and on their terms) was a couple decades ago when I started rock climbing. At first I thought there was something the matter with me because I couldn’t climb the same routes my male friends could, even if I knew I was as fit as they were. This was back when men set most of the routes, which meant they both rated how difficult they were and got to name them. (I’ve lost count of the number of routes that have the word bitch or nuts in them.)

In America the average man is 5'9", but the average woman is 5'4". Those crucial five inches (or more) mean that men and women will have a completely different experience of the same path. Of course, shorter-than-average men are also stuck with the routes that taller men set. But for women, it’s not just about climbs or trails.

For centuries, men have been treated as the default gender, as if the entire world is built for them. Even when men don’t want to be sexist, their lack of awareness of how gender biases work means they still participate in and uphold a sexist culture, even unknowingly. It also means that it’s not always clear to women what disadvantages we face. This is the world we were born into; it can be hard to accept how much of it is natural and how much is truly man-made.

Here’s some of what we’ve learned: In offices, thermostats are set lower, calculated for men who wear suits and have higher metabolic rates. In medicine, dosages are prescribed based on men’s bodies, which has led to dangerous side effects for women. At NASA, gear is designed for men, with too few smaller spacesuits available to send more than one woman to outer space at once. (In March the organization had to cancel its first all-female space walk because it didn’t have two space suits sized for women. You can’t even escape the gender bias by leaving the planet.) Meanwhile, in factories, uniforms and equipment tend to be scaled for the average male face, weight, and height. Even crash-test dummies aren’t safe from the patriarchy, with most modeled off tall men. Should we be surprised that women are more likely to get injured and die in car accidents? No, we should not.

Last month the realization struck anew. A photo of a woman’s breasts, which included beautiful flowerlike milk ducts, went viral. The image was treated like an alien. A never-before-seen specimen that provoked both wonder and some disgust (a response that bore a close resemblance to the ew, cooties reaction that most of us last heard on the playground). The Internet went on to debate just how accurate the photos were, but the point stands: Though 51 percent of the population walks around with at least some version of these structures just below our skin, a fraction of us had ever seen them before.