Used hasOwnProperty to check collection objects had the second argument in them to increase a counter. Finally check counter vs length to check if all values were true.

Truthy values

function truthCheck(collection, pre) {
  // Is everyone being true?

  var counter = 0;

  for (let c in collection) {
    if (collection[c].hasOwnProperty(pre) && Boolean(collection[c][pre])) {
      counter++;
    }
  }

  if (counter == collection.length) {
    return true;
  }

  return false;
}

truthCheck([{"user": "Tinky-Winky", "sex": "male"}, {"user": "Dipsy", "sex": "male"}, {"user": "Laa-Laa", "sex": "female"}, {"user": "Po", "sex": "female"}], "sex");