I definitely do not see the big picture here.

If I am not able to reach the child's getSex() sub in a simply way, then whats the point of the inheritance. I mean the Parent should know about the child's subs.

If I do the inheritance coming from the other direction, so the Son+Daugther are the parents and the Kid is the child then I will be able to reach the subs, but this is logically wrong.

Kid.pm
------
package Kid;
@ISA = (Son);

use Son;

sub new
{
}

Son.pm
-------
package Son;

sub new
{
}

sub getSonSex
{
print("I'm a boy \n");
}

test.pl
-------
use Kid;
use Son;

$kid = Kid->new();

# It's OK
$kid->getSonSex();
[download]

I'm getting more and more confused about these OO terms :)