App.js

import React from 'react';
import ReactDOM from 'react-dom';
import { List } from './List';

class App extends React.Component {
  render() {
    return (
      <div>
        <List type='Living Musician'>
          <li>Sachiko M</li>
          <li>Harvey Sid Fisher</li>
        </List>
        <List type='Living Cat Musician'>
          <li>Nora the Piano Cat</li>
        </List>
      </div>
    );
  }
}

ReactDOM.render(
  <App />, 
  document.getElementById('app')
);

List.js

import React from 'react';

export class List extends React.Component {
  render() {
    let titleText = `Favorite ${this.props.type}`;
    if (this.props.children instanceof Array) {
    	titleText += 's';
    }
    return (
      <div>
        <h1>{titleText}</h1>
        <ul>{this.props.children}</ul>
      </div>
    );
  }
}