If you die without a will you will not be able to choose who receives your assets. Instead, your closest relatives or heirs inherit your wealth according to intestate succession laws.
Intestate succession laws control which surviving family members of the decedent inherit their assets after probate when the person did not leave a will. The statutory laws identify the decedent’s relatives that should inherit the money. Who inherits what depends on which relatives are still alive when the person dies. Generally speaking,
When a decedent is married and has children, the spouse receives part of the estate and the children receive the rest.
If the decedent is unmarried at the time of death and had children, the laws dived the estate equally among the children.
When a decedent is unmarried and childless, the person’s parents inherit the estate.  If the decedent’s parents are not living, the person’s siblings inherit equal portions of the estate.
If the person does not have a surviving spouse, children, parents, or siblings, then the person’s grandparents, aunts and uncles, and cousins can inherit.
Keep in mind, there are many other variations of how intestate laws work. You can read more about California’s intestate succession laws here.