I am a Muslim and my parents are not. They have written in their will that whatever
assets they have will be divided between myself, my brother and my sister (who
are also not Muslims).
What is the Islamic ruling on inheritance for Muslims whose parents are non-Muslim?
Praise be to Allah.
A Muslim is not permitted to inherit anything of the wealth of a non-Muslim relative, as the Prophet (Peace and Blessings of Allah be upon him) said: "The believer does not inherit from a kaafir (disbeliever) and the kaafir does not inherit from a believer." (Reported by al-Bukhaari, al-Fath 4283). According to another report, he said: "The Muslim does not inherit from a kaafir and the kaafir does not inherit from a Muslim." (al-Bukhaari, 6764). The Messenger of Allah (Peace and Blessings of Allah be upon him) also said: "People who belong to two different religions do not inherit from one another." (Reported by Abu Dawud in al-Sunan, Kitab al-Faraa’id, and deemed hasan by al-Albaani in Saheeh al-Jaami‘, 7614) - because when the ties of religion are cut, the ties of inheritance are also cut, because the former is the basis of the latter.
However, if a non-believer makes a will leaving one-third or less of his wealth to his child (son or daughter), one is entitled to take it, because this is a will as opposed to inheritance according to a non-Islamic system. This difference is well-known in Islamic fiqh.
And Allah knows best.