The cover story of this month’s New Republic tells us what we can see with our own eyes—that people are waiting longer to have children. The average age of first-time mothers has increased by about four years since 1970, from 21.5 years to 25.4 and most American men are waiting to become fathers until about age 28 as opposed to about 23 in the 1970s. What is surprising is how big an impact older parenthood will have on the next generation’s genetic makeup…. More