As the gender pay gap continues to be a hot-button topic for many of us who care about discrimination and inequality, it’s important to recognize that the reason that the average working woman is earning less than the average working man is not based entirely on gender discrimination.

There is indeed historic discrimination that has handicapped women for many decades, but women are and have been making strides at astounding rates. Since the early 1980s more women have been attending institutions of higher education than men. The gap continues to increase as there are now approximately 30% more women than men enrolled in college, and this number is projected to be even higher in 2020. Multiple studies also suggest that women in their twenties are earning more than their male counterparts in the U.K.

But why are only 5% of Fortune 500 company CEOs female? What’s preventing women from further success? Obviously, there are many factors that contribute to this discrepancy but I want to focus on one of them: agreeableness.

One who is agreeable is typically pleasing to the mind or senses of others, avoids conflict religiously, prioritizes a group’s need over his or her own, and strives to make others’ lives more comfortable. The disagreeable person, when asked what he wants, is able to tell you straight away; the agreeable person at times doesn’t even know what he wants because he is so used to living for others.

If personality plays a pivotal role in leadership capability, then unsurprisingly, top managerial positions aren’t meant for those who are conflict-averse and hyper-cooperative. So, those who are more agreeable are less likely to receive a promotion, especially for positions in upper management. Multivariate and univariate analyses in scholarly articles reveal that women tend to be, on average, more agreeable than men, and that plays a considerable role in the average earnings gender gap.

Clinical psychologist and professor of psychology at the University of Toronto Dr. Jordan B. Peterson has addressed the issue by examining the differences between those who are conscientious and those who are agreeable. The former don’t care about your feelings and pay attention only to your level of productivity. The latter will be more understanding of underperformance because, for example, it was a rough week and they understand that you had problems at home. Dr. Peterson says that both traits are needed in an employer, but those who are more agreeable are more likely to be exploited. He continues, “if you want to hire someone to exploit productively, you hire middle-aged women who are hyper-conscientious and who are agreeable because they’ll do everything, they won’t take credit for it, and they won’t complain. And that’s nasty, and it happens all the time.”

Now, being agreeable isn’t necessarily something that you should avoid at all times: there are definitely instances where it may be advantageous to be conflict-averse, cooperative, and altruistic. But, if your goal is to build a career, then you should be wary of excessive agreeableness.

One of the ways that you can help yourself be less agreeable is by simply being more honest with yourself and with others around you. That means speaking your mind even when it has the potential to cause conflict or disagreement. A prerequisite is to actually know what you’re talking about. If you have been studying business and management for years and you know that your method for maximizing revenue is better than that of your colleague, then don’t be afraid to speak up. Focus on personal development: read often, eat healthy, and take care of yourself. Your confidence will rise, and so will your assertiveness. Many men and women have also found psychotherapy to be extremely useful for everyday personal interactions and for this particular issue as well. There are many clinical psychologists that offer assertiveness training sessions in order to help others empower themselves.

To tackle the issue of gender diversity in upper management, affirmative action policies and virtue signaling are not the answers. And no, calling a corporation that has more men than women on its board “sexist” is not the solution either. You need to supply those who want to succeed with the education and truth necessary to do so. The truth is that part of the reason why the wage gap exists is because men tend to be more assertive and disagreeable than women. If we really want to see more women in power, we should encourage and teach women in these situations to be more assertive. Sometimes the truth is disagreeable, but we have to acknowledge it in order to make a difference.