If you indent this block

  if ($choice eq 'a'){
    print "Enter a male name: ";
    chomp (my $name1 = ucfirst lc <STDIN>);
      } if (exists $son_father{$name1}) {
          print "Duplicate name -- try again!\n";
          } else {
              print "Add a father: ";
              chomp (my $add_dad = ucfirst lc <STDIN>);
              $son_father{$name1} = {$add_dad};
              next;
  }
[download]

correctly you can see it is 2 blocks not 1

  
  if ($choice eq 'a'){
    print "Enter a male name: ";
    chomp (my $name1 = ucfirst lc <STDIN>);
  } 

  if (exists $son_father{$name1}) {
    print "Duplicate name -- try again!\n";
  } else {
    print "Add a father: ";
    chomp (my $add_dad = ucfirst lc <STDIN>);
    $son_father{$name1} = {$add_dad};
    next;
  }
[download]

What you want is probably

  if ($choice eq 'a'){
    print "Enter a male name: ";
    chomp (my $name = ucfirst lc <STDIN>);
  
    if (exists $son_father{$name}) {
      print "Duplicate name $name -- try again!\n";
    } else {
      print "Add a father: ";
      chomp (my $add_dad = ucfirst lc <STDIN>);
      $son_father{$name} = $add_dad;
      print "$name added with father $add_dad\n";
    }
    next;
  }
[download]

poj