copy feet

There is a funny thing that we humans do as parents. For some reason we choose to take our new born child's feet, cover them with thick sticky ink and then press each delicate soul onto a piece of paper for posterity. What is our drive to copy feet? What purpose does it serve really? I know why we copy finger prints. I have, many times, had to have my fingers gooed up so that some expert can try to match my unique curves and swirls with others to tell if I am a danger to myself and others, but feet? I don't think babies commit crimes without their baby booties on. It makes me wonder, if I inked my feet today, and made a print of my adult foot, would it be the same as my master print 40 something years ago? Where can I get a big ink pad. . .