I have a problem with my step-mom who is younger than me.?

She thinks it's okay to not pick up after her kids, and to leave a theo house a mess. I have tried talking to her that you're supposed to pick up after your kids, but she seems not to care: my dad either. How do i tell them that it is normal to clean up after your kids if they make a mess? or should I just let them be and destroy their babies futures.??