Why are these baristas all women? My sociology students take a crack at a real-world coffee shop conundrum

Last week I was sitting in a local coffee shop and I made an observation that I decided to share with the students in the college-level sociology course I teach online. Here's what I wrote in a class announcement:

Right now I'm sitting in a coffee shop. It's a busy day, and five people are working—all women. In fact, I've noticed over the years that by far the majority of employees at this coffee shop are women. Here's my challenge question for you: how many possible explanations can you think of for why most employees at a business like this would be of one gender rather than another? I can think of at least four.

Over the course of the week we discussed the question in our class forum, and today I posted this follow-up.

Remember the question I posed in last week's announcement? I wondered why the large majority of employees at a coffee shop would be women. This week we discussed that question in the student lounge, and here were your answers:

• Nepotism: The owner just hires his/her daughters.
• Culture: Because of the culture they're raised in, women may prefer to work at coffee shops more than men do. In addition, one student noted, because of how they're raised (and because of social attitudes?), women might be better at making customers feel comfortable than men are.
• Childbearing: Women who are mothers may find it preferable to work in a flexible serving job rather than at a 9-to-5 desk job.

These are all plausible explanations. I'd like to offer at least a couple more:

• Discrimination: The owner—whether he or she is a man or a woman—might just be sexist, and prefer to hire women.
• Network effects: A lot of people find jobs though the people they know. This is probably especially true in serving jobs, where there are many qualified applicants and a recommendation from a trusted current employee can mean a lot. Since social networks are gendered—women tend to know more women, and men tend to know more men—what could happen is that women get into jobs at this coffee shop, then they tell their women friends about the jobs, and those women are hired, and they tell their friends, and so on.

However this disparity originated, once a workplace is tilting towards one gender, members of that gender feel more comfortable applying there; and members of the other gender feel less comfortable doing so...so there's a vicious circle. Can you see how this process would also work with, for example, race or ethnicity?

It's always interesting to me to see what students come up with in response to questions like this. It's not surprising that they didn't think of the social-network effect, since the power of networks is something it's taken sociologists many decades to appreciate. Thanks in part to the kind of data now available from online networks, sociologists are realizing how powerful network effects can be, and how deeply your social network affects your life and your opportunities. Your grandpa was right: it's not what you know, it's who you know.

What do you think? Are there any other plausible explanations for the coffee-bar gender imbalance I observed?