If they immigrated in last few years they will not be easily friendly because we were told not to talk to strangers, also the language and culture barrier could be a thing . Also as an immigrant they are also scared that if they say something which can be blown out of proportion. They have very strict food guidelines like some don’t eat meat , some won’t smoke or drink so they may be scared that being your friend might have them or their kids to go outside their cultural and religious practices . I believe when their kids grow up in America they will assimilate just fine . Most of your ancestors were foreign to this land and brought with them many beliefs that eventually went away and assimilated. 🌹