js继承注意的地方

    function Father() {
        this.LastName = "Xu",
           this.GetLastName = function () {
               alert(this.LastName);
           }
    }

    var Mother = {
        Address: "XXXXXXX",
        GetAddress: function () {
            alert(this.Address);
        }
    }

    function Son() {
        this.FirstName = "Eason";
    }
    Son.prototype = new Father();
    Son.prototype.__proto__ = Mother;
    var s = new Son();
    s.GetLastName();
    s.GetAddress();
    alert(s.LastName);

如果Son不是function 是对象 就不能这样些，而父类是function的时候是怎么写，要注意区分