I overheard some tweedy types at Starbucks today (prob. graduate students or professors) going on about the increasing numbers of childless couples in the U.S. One of the guys said that 1 in 5 women over 40 do not have any children. This seems wrong to me. U.S. culture almost demands children. I do not know a lot of childless adults (although there are more than a few in my immediate family). Thoughts on this? Do SFers come into contact regularly with 30 to 50 somethings without children?