Is this really the different country with the different language, or "just" the other people? As far as I know, everybody behaves differently towards old schoo

Is this really the different country with the different language, or "just" the other people? As far as I know, everybody behaves differently towards old school friends than towards later friends, colleagues at work, their spouse, and so on. How can we eliminate this effect? A study would need to observe the same group of people, all multilingual, in different langauges. It would be interesting to see whether these behave differently depending on the language (or mix of languages) they use. But I personally doubt it. I believe it is "just" the people.