"My parents' house is red."

Translation: Das Haus meiner Eltern ist rot.

[DuckZero]

Is the definite article absolutely necessary here?

[christian]

Yes.

[vign2211]

Y cant it be Meine Elternhaus..

[christian]

It'd have to be "Mein Elternhaus", but "Elternhaus" is more like the house you grew up in.