it's a matter of
It takes two.
Eso de sobrino es cosa de maricas viejas.
That "nephew" business is for old fags.
— Cidade dos Homens (2007)
No, eso es cosa de la forense.
No, that’s the forensic examiner’s job.
— Los renglones torcidos de Dios (2022)
It's just a matter of a minute.
It's a dog thing.
It's a family thing.