Your little sister can palm a basketball and it really bothers you Is there anything you can do to learn to palm a basketball?
Palming a basketball has mostly to do with the size of your
hands are, so unless your hands grow it is not likely that you will
be able to palm a basketball. You can do hand exercises to increase
grip strength but without large enough hands it would be impossible
to palm a reguatlion sized basketball. There are certain type of
basketballs that are easier to grip, maybe your sister is using one
of these. I wouldn't let it bother you either way.