I am American, and my father's parents were from Lithuania.
I noticed recently, within the last few years, that several English Wikipedia articles were edited by someone with a Slavic background to promote the idea that Baltic languages are more related to Slavic ones than I have heard anyone claim before. I would imagine this is a controversial claim in the Baltic states.
At any rate Baltic languages are famously more conservative than Slavic ones. They are of course related as all indo-european languages are. The only question is how far back in history you have to go for that to be a relevant matter. I do not think they are close enough that it is relevant.
This hasn't been controversial in Latvia at all, at least in 90-00's (not that scientific theories should be judged by how controversial they are among laymen). The theory that I heard in several Latvian schools, is that lithuanians and latvians had a common language with slavs and they got separated somewhere in bronze age. Lithuanian language supposedly is the most archaic language alive (that is closest to proto-indo-european language by some measures). As far as I undestand there is consensus between linguists working in the field, that Baltic and Slavic languages are very close, the only questionable part is whether there was proto-balto-slavic language or whether these languages acquired similarities over time (also, some suggest that slavic languages separated from existing proto-baltic language).
Given tendency for revisionism and troubled past between Baltic states and Russia, one could see how it seems so alien to some people.
I am American, and my father's parents were from Lithuania.
I noticed recently, within the last few years, that several English Wikipedia articles were edited by someone with a Slavic background to promote the idea that Baltic languages are more related to Slavic ones than I have heard anyone claim before. I would imagine this is a controversial claim in the Baltic states.
At any rate Baltic languages are famously more conservative than Slavic ones. They are of course related as all indo-european languages are. The only question is how far back in history you have to go for that to be a relevant matter. I do not think they are close enough that it is relevant.