Why does a daughter inherit half of what a son inherits?

The Canadian position

Canadian intestacy divides equally among children regardless of sex. A will can depart from that, and testamentary freedom makes the departure enforceable — except where a variation claim succeeds.

In British Columbia, section 60 of WESA gives a child standing to apply to vary a will. In Grewal v. Litt the court varied wills that had left four daughters 6.6% of a $9 million estate, holding that cultural or religious reasoning did not justify the disparity.

The Islamic position

The ratio applies where sons and daughters take together as residuary heirs. Where no son survives, a daughter takes a fixed share — one half alone, or two thirds shared between two or more.

The classical explanation ties the difference to obligation: a brother carries maintenance duties toward family that a sister does not, and a woman's own property and mahr remain hers.