问React事件处理程序:为什么父事件没有被子绑定覆盖

EN

class App extends Component {
  state = {
    todos: []
  }


  // Toggle Complete
  markComplete = (id) => {
    this.setState({ todos: this.state.todos.map(todo => {
      if(todo.id === id) {
        todo.completed = !todo.completed
      }
      return todo;
    }) });
  }

  render() {
    return (
        <TodoItem markComplete={this.markComplete}  />
    );
  }
}

export class TodoItem extends Component {

  render() {
    const { id, title } = this.props.todo;
    return (
        <input type="checkbox" onChange={this.props.markComplete.bind(this, id)} /> {' '}
    )
  }
}

  markComplete = (id) => {
    this.setState({ todos: this.state.todos.map(todo => {
    ^^^^ why it is not child
      if(todo.id === id) {
        todo.completed = !todo.completed
      }
      return todo;
    }) });
  }