Why is the younger sister always smarter?

The last weekend I went to Bombay (Mumbai) to see a girl. Well, it was arranged in a very typical marwari fashion but I still manged to convince my parents to let us dine out so that we get some time to talk comfortably.
Oh yeah, I went to Bombay all alone. So here were we (I, my local cousin and his family, and Her family, but her) having a lavish and exotic breakfast in a posh dining room, when suddenly the girl appears. Oh wait! I guess you too got confused, no it is not the girl I went to see, but her sister - the younger sister.
"I am fine. How does it matter. I see so many girls around, I dont have to start judging everyone".
I waited till the incessant formalities got over and went back to the royal drawing room. Then came the time for the marwari girl to make her public appearance.
"Ok I dont have to marry every girl I see. Behave nicely".
So as per the plan, we went for the Lunch. JW Marriot - One of the most expensive and beautiful hotel in Bombay. Sitting at 90 degree to each other, we were talking about general things. After an hour of one-to-one talking, came the younger sister. So both of them start telling about each other and about themselves. Here goes another hour.
"Well, why is the younger sister more practical, more chirpier, more beautiful and more slim always".
I laughed on the nature's law and wondered why the grass on the other side always greener.

Decision making

Let your heart decide what to do and brain decide how to do it.
Problem comes when the brain decides what to do and heart decides how.