What am i missing here?

package com.codegym.task.task06.task0621;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/*
Cat relations

*/

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        //for(int i=0;i<6;i++){

            String grandFatherName = reader.readLine();
            Cat grandFather = new Cat(grandFatherName);

            String grandMotherName = reader.readLine();
            Cat grandMother = new Cat(grandMotherName);

            String fatherName = reader.readLine();
            Cat father = new Cat(fatherName, null, grandFather);

            String motherName = reader.readLine();
            Cat mother = new Cat(motherName, grandMother, null);

            String sonName = reader.readLine();
            Cat son = new Cat(sonName, mother, father);

            String daughterName = reader.readLine();
            Cat daughter = new Cat(daughterName, mother, father);

            System.out.println(grandFather);
            System.out.println(grandMother);
            System.out.println(father);
            System.out.println(mother);
            System.out.println(son);
            System.out.println(daughter);
        //}
    }

    public static class Cat {
        private String name;
        private Cat father;
        private Cat mother;

        Cat(String name) {
            this.name = name;
        }

        /*Cat(String name, Cat parent) {
            this.name = name;
            this.parent = parent.name;
        }*/

        Cat(String name, Cat mom, Cat dad){
            this.name = name;
            this.mother = mom.name;
            this.father = dad.name;
        }

        @Override
        public String toString() {
            if (mother==null && father==null)
                return "The cat's name is " + this.name +", no mother, no father";
            else if (mother==null)
                return "The cat's name is " + this.name + ", no mother, " + father.name + " is the father";
            else if (father==null)
                return "The cat's name is " + this.name + ", " + mother.name + " is the mother, no father";
            else
                return "The cat's name is " + this.name + ", " + mother.name + " is the mother, " + father.name + " is the father";
        }
    }

}