Etydhv

My friend asked me a question today:

Woher kommen deine Eltern?

and I wanted to answer

My parents come from Afghanistan.

I know that the nationality in German for "Afghan" is afghanisch with die Afghanin and der Afghane for the respective individuals.

I failed to find any source for when the people in concern are plural.

What happens in that instance? Do we add the plural ending to "afghanisch" i.e. afghanische or what happens?

I thought it would be

Meine Eltern sind afghanische

but I'm not sure.

EDIT my other thought was

Meine Eltern sind Afghanen.

but again I'm not too sure.

Your thought in the edit was correct: If you want to refer to multiple Afghans in German, the plural noun Afghanen is used. It comprises male and female individuals alike.

Meine Eltern sind Afghanen.

^{(My parents are Afghans.)}

However, if you want to explicitly refer to female Afghans, the noun Afghaninnen, which is the plural of Afghanin, is used.

Heute traf ich zwei Afghaninnen.

^{(Today I met two Afghan women.)}

The word afghanisch is an adjective. Its role is to modify noun phrases.

Das ist eine afghanische Blume.

^{(This is an Afghan flower.)}

Das sind afghanische Blumen.

^{(These are Afghan flowers.)}

Direct translation of your English sentence:

Meine Eltern kommen aus Afghanistan.

That avoids all the hassle of finding out how the adjectives must be declinated.

Otherwise you can write:

Meine Eltern sind afghanisch (no -e).

But:

Ich habe afghanische Eltern.

Don't ask me about the rules for this: I speak the language pretty well, but don't know much about the rules behind this, i.e. when to declinate or when to use the base form of the adjective.

You can also write:

Meine Eltern sind Afghanen:

Meine Mutter ist Afghanin und mein Vater is Afghane.

Woher kommen deine Eltern?

There's no need to return a full sentence by repeating »Eltern« and »kommen«, the most simple (and probably most common) answer would be:

Aus Afghanistan.

Some say just

Afghanistan.

which is less polite, because one may get the impression that you want to kill the conversation instantly by giving a minimal answer.