This is a first draft crack at traversing a tree looking for undefined. Could definitely be more performant, but it works for what I need.

find deeply nested value of undefined

function filterDeep(humans) {
    return humans.map((val, key) => {
    	if(Array.isArray(val)) {
      	filterDeep(val);
      } else if(typeof val === "object") {
      	filterDeep(Object.values(val));
      } else if (val === undefined) {
      	console.log(typeof val, val, key);
        return true;
      }
    }).length > 0;
};

const people = [
	{
  	name: undefined,
    sex: 'male',
    children: [
    	{
      	name: 'Jeffrey',
        sex: 'male',
        children: [
        	{
          	name: 'Alicia',
            sex: 'female',
            children: undefined
          }
        ]
      },
      {
      	name: 'Apu',
        sex: 'male',
        children: [
        	{
          	name: 'Josiah',
            sex: 'male',
            children: []
          }
        ]
      }
    ]
  },
  {
  	name: 'Jennifer',
    sex: 'female',
    children: [
    	{
      	name: 'Josh',
        sex: 'male',
        children: [
        	{
          	name: 'Erica',
            sex: 'female',
            children: [
            	{
              	name: 'Alex',
                sex: 'male',
                children: []
              }
            ]
          }
        ]
      },
      {
      	name: 'Laura',
        sex: 'female',
        children: []
      },
      {
      	name: 'Jordan',
        sex: 'male',
        children: [
        	{
          	name: 'Ezekiel',
            sex: 'male',
            children: []
          }
        ]
      }
    ]
  }
]

const thing = filterDeep(people);
console.log('wut',thing)