If one of my children predeceased me, do my grandchildren inherit their parent's share in Ontario?

Yes. Ontario's intestacy rules use a principle called "representation" (sometimes called per stirpes distribution). If one of your children dies before you, that child's share of your estate passes to their own children — your grandchildren — rather than being divided among your surviving children.

For example, if you have three children and one predeceases you leaving two grandchildren, your estate would effectively be divided into three equal parts: two parts go to your surviving children, and the third part is split equally between the two grandchildren who represent their deceased parent.

If the predeceased child left no children of their own, their share typically goes back into the pool and is divided among the surviving children. The per stirpes rule ensures that a branch of the family is not entirely cut out simply because their parent died first. A will can modify this structure — for instance, by directing that all grandchildren share equally regardless of their parent's situation.