How to do deep copy to Javascript object, and call the parent's own prototype method

DeepCopy.js

/* Title: Deep Copy Object Properties
 * Refference: https://github.com/shichuan/javascript-patterns/blob/master/code-reuse-patterns/inheritance-by-copying-properties.html
 * Description: an object gets functionality from another object, simply by copying it
 * Only the properties will be copied. The prototype will not
 * it is generally not recomended to copy the prototype over
 */

/* deep copy */
function extendDeep(parent, child) {
    var i, toStr = Object.prototype.toString,
        astr = "[object Array]";

    child = child || {};

    for (i in parent) {
        if (parent.hasOwnProperty(i)) {
            if (typeof parent[i] === 'object') {
                child[i] = (toStr.call(parent[i]) === astr) ? [] : {};
                extendDeep(parent[i], child[i]);
            } else {
                child[i] = parent[i]; //primitive value can be copied over
            }
        }
    }
    return child;
}

function Man() {
    this.counts = [1,2,3];
    this.reads = {paper: true};
}

Man.prototype.slapChild = "Slap!";

Man.prototype.counting = function() {
    return "current counts from this is " + this.counts;
}

var dad = new Man();
var kid = extendDeep(dad);

kid.counts.push(400);
kid.counts; // [1,2,3,400]
dad.counts; // [1,2,3]
dad.slapChild; // "Slap!"
kid.slapChild; //undefined
dad.reads === kid.reads; // false. Both aren't refferencing to the same object

//now, what if we would like to call the prototype method from dad?
dad.constructor.prototype.counting.call(kid); // "current counts from this is 1,2,3,400"