Watch the girls eat a cookie and you can see how vastly different they are. McKenzie carefully eats the cookie, leaving all the m&m's for last. She always does this, saves the best for last. In fact, she'll eat so much of the cookie that she will be full and decide to save the candies for later.
Kaia, on the other hand, eats the best first. She picks each m&m off the cookie, eating as she picks. Then, when the cookie is depleted of candy, she'll take a bite and, if it's not a particularly chocolaty cookie, she'll leave the rest on the counter.
Their cookie-eating methods so mimic their personalities in other areas it's astounding. Kenzie, the patient, thinker with a plan (who sometimes misses out on the best of things because she's so careful), and Kaia, the impulsive, act now/think later monkey with no plans for what will happen in the next instant (who often gets into trouble due to lack of foresight).
How can two people, raised under the same roof, be so, so different?