Judging from the many internet rants ("10 Things Childfree People Will NEVER Understand", "Why Mums and Dads Are Selfish and Annoying"), you'd think parents and non-parents are entirely different species. Something happens the moment a baby is born -- adult friendships that once seemed so easy become filled with obstacles ("What do you mean you can only eat dinner at 4:45PM?" "Why don't you answer my phone calls, ever?" or "Sorry, I don't have to time to hear about your promotion/mother-in-law problems/recent holiday -- the baby is crying").