Memes

I mean they are fairly similar. They share a lot of vocabulary, their nouns have corresponding declensions, verb conjucations are similar, there are a lot of other similar grammar constructions, and the Latin alphabet is mostly derived from the Greek alphabet, too.

Edit: Classical Greek and Classical Latin, at least. Modern Greek and Romance languages like Italian are further diverged from those ancestor languages to the point that they are difficult for modern speakers to even parse.