There is plenty of data to show that diversity is good for the workplace. But in general we don’t really create it for ourselves, because we like to work with people who are similar to us.

“In terms of innovation, diverse teams way outperform non-diverse teams, but people are very comfortable working with people they have worked with in the past or people who are like them,” says Frans Johansson, author of Medici Effect: What Elephants and Epidemics Can Teach Us About Innovation.

Before you start commenting about how you are the exception, and your office is diverse, let’s be clear on what diversity is. The research about diversity at work is about diversity of experience, perspectives or work styles. This means that teams you might assume are diverse may not be – for example a multi-racial team of prep-school and Ivy-league graduates might have had a homogenous experience. This also means that places we typically think of as diverse, like San Francisco, are actually more homogenous than we realize (#6).

Diversity is a popular idea, but we misuse the idea of it all the time. We can learn a lot about diversity from preschools, by way of politics.

Wisconsin recently voted to ban gay marriage. Voters of Madison, where I live, strongly opposed this measure. The sentiment here is indignanation that their own state passed such a discriminatory law. Yet gay marriage is not about diversity in Madison. Gay people are part of the mainstream here, and are widely accepted.

A better gauge of Madison’s ability to accept diversity is whether their school system is willing to spend the money to comply with the Individuals with Disabilities Act at the preschool level. And the answer is a resounding no. The school system violates case law precedents and no one is standing up for the kids who are different and demanding that they receive fair treatment under the law.

Another preschool example: New York City preschools cost more than $10,000 a year. Most offer no financial aid, and on top of that, the admissions process is so difficult and grueling that many parents hire consultants to help get their kid in. (I hired a very popular one for $4000.) Almost all the schools talk about the importance of diversity, but how you can have diversity among people who will pay $10,000 a year for preschool? You have already eliminated 99% of the U.S. population.

Do you know where there are truly diverse preschools? In Head Start, where kids come to school speaking no English, where some kids have parents with Ph.D’s, and some have parents who can’t read. And you know what? These classrooms are very, very difficult to manage, because diversity is very difficult to manage.

And this brings me back to Johansson, who says that truly diverse teams are not easy. “Making diversity work requires a lot of effort up front. So you won’t get results as fast as you’re used to.” People must know this instinctively because we talk about diversity all the time, and create it only rarely. “People talk about it because they know they should,” says Johansson, “But they just don’t believe it.”

So what can you do to change things?

1. Understand that we each have an inherent bias against diversity.

2. Test your team for diversity. Did you mesh right away? Then you’re probably not coming from such different perspectives.

3. Embrace the multi-generational workplace. The reason generation is such a big issue in the workplace today is that in many instances, it creates diversity that you can’t escape. Usually you can decide to not to work with the person who would bring diversity to your team. You don’t need to give a reason, you just choose someone who is more like you. But what do you do when a whole generation is not like you? You have to learn to work with someone who has different pespectives.

So, the bad news is that we’ve been talking about diversity for twenty years, and accomplishing very little. The good news is that the fireworks at the multigenerational workplace are not just conflict, but the first signs of widespread diversity at work.