How to properly recall a function using custom MVC - php

Question

Hi and good day to you all..
I'm new to MVC's/model-view-controller frameworks. I've made my own by reverse-engineering a custom MVC framework I've got from a friend of mine, so far it's all going good and smooth until I got to this part where I need to recall a function inside the function it self.. I'm currently creating a binary tree website and need to output values inside the table, what I'm trying to do is call a function and fetch all values and put them inside an array for later referencing.
This is my code in the model folder.
public function getGenealogy($parent) {
$this->db->sql('SELECT * FROM accounts WHERE sponsorUpline = ?');
$this->db->bindValue(1, $parent);
$this->db->execute();
while($row = $this->db->fetch()) {
echo $row['serialNumber'];
$this->getGenealogy($row['serialNumber']);
}
}
And this is my code in the controller folder
public function index() {
$memberAccounts = $this->db->getMemberAccounts();
$getDirectReferal = $this->ddrs->getDirectReferal();
$genealogy = $this->bg->getGenealogy($_SESSION['activationCode']);
$data = [
'memberAccounts' => $memberAccounts,
'getDirectReferal' => $getDirectReferal,
'genealogy' => $genealogy
];
$this->view('dashboards/dashboard', $data);
}
As you can see, I'm trying to call the function inside of the function but what happens is that it doesn't call it self, I tried doing the same method but not with MVC and it works fine.
So my conclusion is there's something wrong about my code that I can't seem to grasp.
Also it outputs the children twice but with same values.
This is my database.
This is the output.
.
Any ideas or help would be appreciated.