What happens to inheritance if a family member converts to another religion?

This is a genuinely debated area with real practical consequences. The classical majority position across the four Sunni madhabs is that inheritance does not pass between a Muslim and a non-Muslim — meaning a person who leaves Islam (or a relative who was never Muslim) traditionally would not inherit from, or bequeath to, a Muslim relative through the fixed fara'id system. Some contemporary scholars and fatwa bodies have revisited or nuanced this position, particularly regarding non-Muslim relatives (as opposed to apostasy specifically), and there is more contemporary discussion here than on most inheritance questions.

In India, this question also intersects directly with civil law: conversion out of Islam generally moves a person outside the scope of the Muslim Personal Law (Shariat) Application Act, 1937 for their own succession, which changes which law actually applies to their estate. Given both the genuine scholarly nuance and the civil-law dimension, this is not a question to resolve from general principles alone — anyone facing this situation should get a specific ruling from a qualified scholar and, given the Indian legal context, legal advice as well.

Source: majority Sunni fiqh position on inheritance and religious difference; contemporary scholarly discussion (e.g. Islamweb fatwa on confirming apostasy before exclusion from inheritance); Muslim Personal Law (Shariat) Application Act, 1937 as the Indian civil-law context.