printDad function help

Not strictly related to the question but ...
Be careful about

void printDad(Person p) 

It actually doesn't refer to the person you mean, but to a copy of it.
That -because of how C++ default copy constructor works- has the same members values (hence point to the same mom and dad) and hence incidentally will work the same, but it is actually a "temporary brother".
Pass a pointer or a reference, not a value.

Also, learn to use const for member function that don't modify the object, and const& for parameters. You'll avoid a lot useless copy.

void printDad(Person& p) // cause i cant see a copy constructor
{
  if(p.getDad())
    cout << p.getDad()->getAge() << endl;
  else
    cout << "orphan" << endl;
}

or implement a copy constructor:

class Person
{
  Person* mom,
  *       dad;
  int     age;
public:
  Person(){ mom=dad=0; age=0; }
  Person(Person& init){ mom=init.mom; dad=init.dad; age=init.age; }
   // the others
};

Good luck.