I mentioned recently that the rising generation may not be that different from those which have gone before, under "Stray Thoughts." I focused there on rebellion and authority, but the idea may generalise. I have long thought that the differences between one generation - of Boomers, or Millennials, or whatever - and the ones before and after are largely journalism and pop-social science games. Even though the generation born in the mid-90s and after looks very different and shows some measurable distinctives, I think even they are much like previous groups.
What is different is that as society changes, different behaviors get rewarded, so who gets famous, who gets rich, who gets noticed, who wields social power - all these change slightly or greatly in response. If you change the pay scale or the strike zone or the rules on traveling, different athletes will succeed. Yet the number of athletic people who have the drive to excel will likely be about the same, decade after decade. We likely have the same number of busybodies, but our cultural and especially legal punishments of those they want to interfere with have made them more powerful. HR doesn't want the company to come under increase regulatory scrutiny or worse, get sanctioned, and focuses on that rather than on getting quality hires and keeping quality personnel. This reinforces itself.
Whether we have more criminals is affected by drug use, and the rewards for crime versus the risks for engaging in it. Head injury and other trauma likely has some effect. But the percentage of people at risk to be dangerous likely doesn't change much. What their rewards and incentives are is what changes.
There may be secular changes over time related to culture and teaching, but I don't think these change quickly. Stuff makes the news and lots of people try to make a living commenting on how the world is changing, so we are likely given a false picture of what is changing and what is not. I will stick with my view that we underestimate genetic influences, and underestimate rewards and punishments for behavior, and overestimate the effect of fashions in education and both the popular and classical arts.
Young people marry less often and have fewer children now. (James just had a post that touches on family formation.) There are a hundred theories as to what cultural changes are driving this, and if you talk to the individuals involved they can describe at length what they think their reasons are. And young people in other regions, classes, or countries will give different reasons. But marriage is no longer an economic necessity, and children are more and more expensive, especially when taking the measurement of insuring that they have a life that looks about as prosperous as yours, or better. That is true in an increasing number of countries. Looking for cultural explanations may be a form of evasion, of not admitting that what we have done in terms of zoning and housing and educational costs is most of the explanation.