React，onMouseEnter事件触发所有项目而不是一个悬停的项目？

import React from 'react';

class ParentComponent extends React.Component {
  handleMouseEnter = () => {
    console.log('ParentComponent onMouseEnter');
  }

  render() {
    return (
      <div onMouseEnter={this.handleMouseEnter}>
        <ChildComponent />
      </div>
    );
  }
}

class ChildComponent extends React.Component {
  handleMouseEnter = () => {
    console.log('ChildComponent onMouseEnter');
  }

  render() {
    return (
      <div onMouseEnter={this.handleMouseEnter}>
        ChildComponent
      </div>
    );
  }
}

export default ParentComponent;