Said every startup....well, ever.
The concern over cultural changes within an organisation is one every Founder or Exec team has, yet it is the one thing you cannot escape....change is coming.
Culture - the ideas, customs, and social behaviour of a particular people or society.
Ideas, customs, behaviours, people, societies; they all change. So if culture by its very definition is a constantly changing entity, then why would startup culture remain? But more importantly, why do you want it to?
If your culture is to remain static, then every new team member will be a replica of what you have. Ideas won't be tested, behaviours won't be challenged or improved and ultimately you won't innovate. Your culture will DIE (sorry, but it's true)
On a daily basis I am asked by candidates to describe the company's culture. My heart sinks each time, because I then have to explain why the culture continues to change and therefore the answer may not be what they want to hear. But here's the thing, if you are growing your team at a significant rate then the culture can be changing rapidly (in the height of busy recruitment campaigns this can be as much as every other week). So how do you pin it down? Or more importantly how do you hold on to it?
You don't.
If the ideas, customs and behaviours are constantly changing each time someone new joins your team, then your culture will continue to change. And change is good! I often tell founders that the team that gets you from series A to B, won't necessarily be the team that gets you from B to C. Not because you should replace your entire team, but you might! And the ideas and behaviours of those that remain might change, they will learn from mistake and change opinions and direction. New team members will join, new behaviours will take hold, new ideas will be tested and a new society (or team) will grow.
If you believe culture is drinks on Friday, variations of the company t-shirt, the ping pong table and beanbags (for the love of God get rid of the beanbag's) then I get why you are freaking out...but that's not culture, it's just image.