【python】为什么父变量地址在子类对象中相同

以下是我的python代码。我认为output_ports和input_ports的地址不同。

class test():
    def __init__(self) -> None:
        pass

class INode(object):
    node_name = "INode"
    config = None
    output_ports = []
    input_ports = []
    def __init__(self) -> None:
        super().__init__()
        pass

    def NodeStart(slef):
        pass

    def GetOutputPort(self):
        print(self)
        index = len(self.output_ports)
        # self.output_ports[index] = test()
        self.output_ports.append(test())
        # return self.output_ports[index]
        
    def GetInputPort(self):
        print(self)
        index = len(self.output_ports)
        self.input_ports.append(test())

class AdbCollectNode(INode):        
    def __init__(self) -> None:
        super(AdbCollectNode, self).__init__()
        self.node_name = "s"
        pass

def LinkNode(node_output, node_input):
    node_output.GetOutputPort()
    node_input.GetInputPort()

if __name__ == '__main__':
    adb_node = AdbCollectNode()
    adb_node_1 = AdbCollectNode()
    adb_node_2 = AdbCollectNode()
    LinkNode(adb_node_1, adb_node_2)
    LinkNode(adb_node_1, adb_node)
    print(id(adb_node_1.input_ports))
    print(id(adb_node.input_ports))
    print(id(adb_node_2.input_ports))
    print(id(adb_node_1.output_ports))
    print(id(adb_node.output_ports))
    print(id(adb_node_2.output_ports))

id（）输出如下：

454938259245493825924549382592454935622445493562244549356224

我认为子类变量地址是相同的为什么不一样？