Parent

class Base(object):
    def __init__(self, parent = None):
        print("Base created")

class ChildA(Base):
    def __init__(self, parent = None):
        Base.__init__(parent)

class ChildB(Base):
    def __init__(self, parent = None):
        super(ChildB, self).__init__(parent)

ChildA()
ChildB()

Наследование Parent

class Base(object):
    def __init__(self, parent = None):
        print("Base created " + str(parent) )

class ChildA(Base):
    def __init__(self, parent = None):
        Base.__init__(self, 'child A')

class ChildB(Base):
    def __init__(self, parent = None):
        super(ChildB, self).__init__('child B')

ChildA()
ChildB()

Base created child A

Base created child B