Investment and love

[Dan Ariely on why we love our kids so much](http://www.bakadesuyo.com/2013/03/interview-nyt-bestselling-author-dan-ariely-talks/) (and more than others):

> Kids really come with no instructions. Very tough to deal with, difficult, complex, but incredibly involving and time consuming and I think the love that comes out of it is an example of the effect of a tremendous investment.