Запутался уже в этой задаче, подскажите пожалуйста, в чем я здесь допускаю ошибку....

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));

        String grandfatherName = reader.readLine();
        Cat catGrandfather = new Cat(grandfatherName);

        String grandmotherName = reader.readLine();
        Cat catGrandmother = new Cat(grandmotherName);

        String fatherName = reader.readLine();
        Cat catFather = new Cat(fatherName, catGrandfather);

        String motherName = reader.readLine();
        Cat catMother = new Cat(motherName, catGrandmother);

        String sunName = reader.readLine();
        Cat catSun = new Cat(sunName, catFather, catMother);

        String daughterName = reader.readLine();
        Cat catDaughter = new Cat(daughterName, catFather, catMother);

        System.out.println(catGrandfather);
        System.out.println(catGrandmother);
        System.out.println(catFather);
        System.out.println(catMother);
        System.out.println(catSun);
        System.out.println(catDaughter);
    }

    public static class Cat {
        private String name;
        private Cat parent1;
        private Cat parent2;

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

        Cat(String name, Cat parent) {
            this.name = name;
            this.parent1 = parent;
            this.parent2 = parent;
        }

        @Override
        public String toString() {
            if (parent1 == null && parent2 == null)
                return "The cat's name is " + name + ", no mother " + " no father";
            else {
                if (parent1 == null && parent2 != null) {
                    return "The cat's name is " + name + ", no mother " + " father is " + parent2;
                } else {
                    if (parent1 != null && parent2 == null) {
                        return "The cat's name is " + name + ", mother is " + parent1.name + " no father";
                    }
                }
            }return toString();
        }
    }
}