People of some nationalities are better at learning languages than other nationalities.
Even though it is easier to learn a language closer to your own. It is not because their own language is very close to the target language.
People who are good at learning one foreign language are good at leaning any language however different or further or is from our own.
It would seem that people can somehow learn languages that are similar to their own, but it is impossible to them to learn a very different language. Here or doesn't mean that their linguistic abilities vary depending on the language they are trying to learn.