Hi,
You can perform Windows genuine validation via Settings. Just go to the Start menu, click Settings, then click Update & security.
Then, navigate to the Activation section to see if the OS is activated. If yes, and it shows "Windows is activated with a digital license ", your Windows 10 is Genuine.
For your reference:
About Genuine Windows
https://support.microsoft.com/en-us/help/15087/windows-genuine
Hope above information can help you.