The voice
I started to easily recognize Central and Eastern Europeans based on their body position. Also the way they walk, take a seat, move, their entire body posture, all these things give away CEE natives.
Then there is the voice.
The way their voice sounds. They have a particular sound. It's neither the accent, nor the language. It's just the voice, the sound of it. It's a mix between tone, pitch and the rhythm of speaking. What does this say about someone?
Well, it kind of says it all. It reveals details about someone's level of education or socio-economic background. It also shows psychological traits and cultural background. Sometimes even more sophisticated things like religious orientation.
Voices don't have accents, nor are they tied to certain languages. But they are alive. The way your voice sounds expresses who you are. There is nothing that you can hide the moment you start talking, no matter if you speak in your mother tongue or in English or any other language.