I don't understand.

Question

Mis hermanos mayores, ____ son gemelos, tienen personalidades diferentes.i know that los cuales is possible but feel so awkward. should it not be erased from an option? this sounds very invasive.

Silvia Piriz · Accepted Answer

Hola Carmen L.
Your example requires a relative pronoun to refer back to "mis hermanos mayores". In formal written Spanish, “los cuales” is a grammatically correct option:
“Mis hermanos mayores, los cuales son gemelos...”.
However, you're absolutely right that it can sound overly formal or even awkward in everyday conversation.
In more natural, fluid Spanish—especially spoken or informal writing—we would typically use “que”:
“Mis hermanos mayores, que son gemelos, tienen personalidades diferentes.”
This is the most commonly used form and feels much smoother to native ears. Still, “los cuales” appears in the test as a valid grammatical alternative, and it’s important for learners—especially at B2 and beyond—to recognize it, even if it's not always the most idiomatic choice.
So while it might sound a bit stiff, it’s included to help you become familiar with formal structures, which are especially useful in written or academic contexts. But rest assured: “que” is perfectly fine here and is indeed the most natural choice!
Let us know if you'd like more examples or a deeper explanation—we’re happy to help!
Saludos
Silvia