Proof that Android is Linux

Is this a secret? The android operativsystem wiki clearly says this.

"Android is a mobile operating system developed by Google, based on the Linux kernel and designed primarily for touchscreen mobile devices such as smartphones and tablets." https://en.wikipedia.org/wiki/Android_(operating_system)

I am not sure why now, but I had some expectation of getting a different result. Just me being an idiot. I use the same code all the time to differentiate Windows from Linux.

Well it is, effectively, a custom Linux distribution.