Why can they learn a foreign language quicker than me?

Of course there are always people who work harder than others _ they do their homework no matter what. Sometimes I also suspect it's about genetics!? Some people seem to belong to this kind-of-species of people who just seem to enjoy learning a new language: were they born like this!? 

The universal truth is: 1) it's hard to learn a new language, it takes time and require a strong motivation; 2)  paradoxically, everybody can do it 3) BUT, we do not have the same starting point. 

An important factor that will influence our ability and rapidity to learn a new language is the distance between the language(s) that we already know, and the new language we want to learn. This distance can be evaluated according to the historical roots of your native language.

Languages evolve. Populations migrate and encounter each other or, on the contrary, disconnect from each others due to migrations and wars. As people move, and as their new environment changes, so does their language. Grammar and pronunciation change. New words appear often borrowed from encounters with other cultures, while some words disappear because the population does not need to use them anymore. For example many technological words borrowed from English have entered the vocabulary of various languages due to technological developments (we twitt, we google…) while some old jobs have disappeared and with them the names and verbs describing the activities and the objects and tools involved. Did you ever have this experience of visiting our home country and discover new words and new expressions that did not exist or were not use with the same meaning, while we were still living there?  

Among the many large families of languages from the past, the proto-Indo-European language is thought to have been at the origin of many languages now spoken in Europe and Eastern Asia: Germanic languages, Latin languages, Indic languages, Iranic languages, Celtic languages, and others. Common roots, similar features.

English and Dutch, for example, used to be one language, which was of course neither English, neither Dutch yet, but their common proto-language, the Proto-Germanic language. They have the same roots, the same ancestor language, and share a lot of vocabulary and grammatical features in common. 

A practical consequence is that in language classes, you will observe that people learn much quicker than others. It's often a question of previous knowledge of similar languages. People coming from countries where the language has similar roots as the language you are learning will find it easier to learn this second language. For example Chinese expats who never learned English or another Indo-European language will have much more difficulty learning Dutch than people who have already learned English or German. Inversely, languages in Pacific Asia or Sub-Saharan Africa will be difficult to learn for Europeans. For the same reason, as you can read English, you will find it easier to learn Dutch or German than a Spanish, Italian or French person who has never learned any Germanic language before.

See below this 'language tree'. It illustrates the proximity of languages and their common roots. Languages with roots that are closer in time have evolved more recently from a common proto-language and therefore have still many words, phonemes and grammatical points in common.

This should not be an excuse for not trying to learn a local language, but this should also tell you that when people around you find is easy to learn the language and seem to learn it more quickly than you, don't get discouraged! It might just be that they have in head grammatical structures and words similar to the second language that you are all studying, while for you, it's all new and difficult to memorize all together. 
Besides, once you've learned a foreign language, it will tremendously help you to learn others, especially if they have common roots.  

I hope this helps you to feel encourage to pursue your efforts in learning a second language! 
Wherever you are and wherever you come from, good luck! :-) 

 Picture found on many internet websites - if I find its origin I will acknowledge it's authors, unfortunately I couldn't find where it comes from! If you know, please drop a comment, thanks!