La responsabilidad de cuidar de nuestro abuelo enfermo le incumbe a toda la familia.The responsibility of taking care of our sick grandfather concerns the whole family.
Este asunto incumbe a todos, sea cual fuere su afiliación política.This problem concerns everyone, no matter what their political affiliation.
Eso no incumbe para nada a los demás. La decisión de casarme o no es mía.It's none of anyone else's business. It's my decision whether to get married or not.
¿Qué te dio esa mujer en el sobre? - No te incumbe.What is in the envelope that lady gave you? - It's none of your business.