What it’s like to start a company with your sister

Gillian O'Brien
5 min readDec 17, 2019


So, what’s it like to work with your sister?

Of all the questions I’ve gotten this year about Cherry, this is possibly the one I’ve heard the most.

Sibling relationships come in all different varieties, so I understand why people are surprised when they learn that my co-founder is my sister. Here’s my attempt at demystifying our relationship, and why it works:

Why it works:

For me, there are three major advantages to working with my sister (Emily). They are:

  1. History & familiarity
  2. Core trust
  3. Friendship

Bonus: complimentary differences

1. History & familiarity

In 2010, Paul Graham wrote an article for Forbes titled “What We Look for in Founders”. To conclude the article, PG shared an observation about the co-founders of Justin.tv:

“Emmett Shear and Justin Kan of Justin.tv are a good example of close friends who work well together. They’ve known each other since second grade. They can practically read one another’s minds. I’m sure they argue, like all founders, but I have never once sensed any unresolved tension between them.”

I like to think that (given this logic) we have a leg up, because I’ve known my sister since… well, birth.

It’s true that the length of time I’ve known her (almost 25 years) and the amount of time we’ve spent together has lent itself to creating a deep familiarity and understanding between the two of us. Call it “mind reading” if you want to. 🔮

Deciding to start a company was a huge risk — and though nothing really makes that less daunting, it certainly helped that I had already gone through many of the ups and downs of life with Emily. Work puts an additional strain on a relationship, but we had a strong foundation between us to build from. We entered our relationship as business partners with a prerequisite understanding of how the other “worked”. (How does she respond to stress, success, inconvenience, and day to day challenges?)

We’re in sync. And the description from PG feels super accurate here — we certainly do argue, like all founders, but no disagreements or resentments linger beneath the surface. We know how to communicate and resolve conflict which is an interpersonal skill that builds over time, evolving as the relationship (and the people inside it) evolve.

2. Trust

Aside from the length of time we’ve known each other factor — working with a family member comes with an immediate trust.

Of course, not all family relationships work like this. Emily & I are lucky that we trusted each other upfront. When we had our first conversations about starting a company together, there were no underlying anxieties about ulterior motives or hidden agendas. “If you win, I win” was the way that we felt.

But trust is (hopefully!) about more than just knowing someone isn’t going to screw you over. 😅 In the day to day, we feel equal in the work we’re doing, the time we’re investing, and the value we’re both bringing to the table. We employ a “divide and conquer” mentality to a lot of the work that is done. Emily is technical, while I am not. She develops our product, and directs engineering resources while I handle sales and BD. You need a core trust to allow another person to run a huge chunk of your business like that.

I won’t lie and say that this trust was implicitly as strong as it is now. Trust was always there, but it’s become much stronger as time goes on and we have the opportunity to watch each other shine in our roles, or fail upwards and learn from mistakes.

3. Friendship

The best part of working with my sister is that I like her, and we’re friends. We have the same sense of humor, are nostalgic for the same brands, like the same type of music to be playing in our office (Ariana Grande, specifically) and most importantly: we have the same values and vision for the future.

Startup co-founders spend a lot of time together — so much so that it’s often compared to marriage. It helps to work with someone you have fun with, and someone whose opinion you respect.

Friendship enriches the work that we do. This can mean taking 10 minutes to watch Lucas Cruikshank on YouTube and laugh about something that happened that day — or it could mean being a rock: helping to replenish someones energy stores during an especially hard or uncertain time. We take turns being this person for each other. (insert “get you a co-founder who can do both” meme here).


Complimentary differences

Growing up in the same family means that Emily and I have a lot in common.

That said, we’re very different people. We’re similar in the right ways (see: Friendship). But we’re different in the right ways, too.Emily is technical, analytical, objective, and detail-oriented. I have a bias to action, am a “big picture” thinker, and people-oriented.

10% of co-founders end their relationship within a year of starting a business. 45% break up within four years.

I feel extremely grateful that Emily & I are sisters — and that we have the relationship we have. It’s not lost on me how lucky we are to have had 20+ years to build a friendship and develop good communication skills outside the context of our startup, long before deciding to work together.

This is why/how our relationship works, for those who wonder. 👯‍♀️

But now I’m curious — how did you meet your co-founder, and what do you think makes your relationship work? Could you ever imagine working with your sibling? Share your thoughts in the comments below. I’ll be taking notes. 🙃



Gillian O'Brien

Accelerator Partnerships @ Pilot.com + Venture Partner @ OCVC | YC alum | former Chief of Staff | NYU grad | gillianroseobrien.com