php checkbox checked on edit page

I have 3 tables:

people:
------------------------
peopleID,
firstname

peopletype:
------------------------
peopletypeID,
type

peoplepeopletype (junction table):
------------------------
peopleID,
peopletypeID

On the add form everything is fine, but I have problem to display checkboxes checked for the assigned peopletype

Here is my code.

Retrieve data from peoplepeopletype table :

/*PEOPLE TYPE ************* */

    $stmt = $conn->prepare("SELECT * FROM peoplepeopletype WHERE peopleID=?");


    // set parameters and execute
    if ( !$stmt ) { echo "error"; }
    else if ( !$stmt->bind_param('i', $_GET['peopleID']) ) { echo "error";}
    else if ( !$stmt->execute() ) { echo "error"; }
  else {
      $result = $stmt->get_result();

      while($row = $result->fetch_assoc()) {
          $peopletypeIDfromdb = $row ['peopletypeID'];
          echo $peopletypeIDfromdb;
      }  
  } /* end else */

Display checkboxes :

 <?php /*retrieve peopletype from db */     
 $sql = "SELECT * from peopletype";
$result = $conn->query($sql);

while($row = $result->fetch_assoc()) { 
    echo '<input required="required" type="checkbox" name="peopletypeID[]" value="' . $row["peopletypeID"] . '"'; 
    if  ($peopletypeIDfromdb = $row["peopletypeID"]) { /*problem is probably here
               echo 'checked';
            }
    echo '>' . $row["type"];

}
              ?>

Thanks for your help!