I've read articles about this topic and I've agreed with a lot of what some of them say, but here's my take on it.
My grandmother's generation, raised in the Depression, had nothing. They were often hungry, wore old and oft-repaired clothing, and swore never to do that to their own kids. So the next generation, the baby boomers, were given everything they needed. They got new clothes and lots of food whenever they wanted (I think the invention of the snack, let alone specific snack foods, came at about this time), and luxuries like TV and record players.
Then the baby boomers had kids, my generation. And not only did they give us everything their parents gave them, but we also had cable and central air conditioning and other newly invented luxuries. Plus, divorce became popular in the 70s and 80s and our parents were busy having careers and getting divorced and remarried and doing all the dating in between. And they made up for their absence and preoccupation with gifts. Two families can mean two Christmases, and Mom working late or going out on a Friday night can mean pizza or fast food. So we got spoiled, and fat, as a generation. And now we have kids, and we add our own twist.
My generation, the people I know anyway, seem to fall into 2 main categories. The ones who see divorce as an inevitability (I once heard a woman in her 20s refer to a passing stranger as "my fourth husband", and those who swear never to do it themselves. Oddly enough, the ones who divorce most often tend to come from parents who never did. But the ones who are determined never to divorce often remember how parental divorce affected them or their friends growing up. They remember feelings of neglect and unimportance and don't want to do that to their children. And they remember parents who weren't home. I know more stay at home parents my age than I remember seeing when I was a kid. Our mothers were dating and flirting and finding us step-dads and we want to be there for our kids. And now you have , in addition to the cable TV and central air conditioning, cell phones and laptops. But also helicopter parents. Parents who remember what it felt like when they were bullied and Mom didn't care, so they will storm into the school and fight for their child over the smallest things. Parents who rush their kids to the doctor over any fever or rash or nausea. Parents who practically have Purell pumped into their house via water pipes. (I don't remember my mother ever sanitizing my toys in bleach growing up but now people talk about doing that all the time, and the moms I know who do it seem to be the ones complaining of sick kids the most. Causation or correlation?)
Somehow in the last 3 generations, we've gone from telling our kids to always dress nicely and be polite and respect your elders no matter who they are, to everyone only worrying about their own family and resenting any implication that there might be a greater good out there worth worrying about. It manifests in little ways all the time. A parent who refuses to vaccinate their kid because they think there are too many shots contributes to the diminishing of herd immunity. Germaphobe parents teach their kids specifically not to share. Kids are taught to mind their own business and later, witnesses to public crimes never come forward. There is less of a sense of responsibility to society than there used to be. There is also a growing sense of narcissism. An obese parent feeding their child high-fat high-sugar foods will say "I grew up on this stuff and I'm okay" and honestly believe it. A circumcised father, rather than looking at his perfect baby boy with pride, will demand an unnecessary surgery so that the boy's penis will look like his (which is, of course, the most glorious penis ever to exist). A mother who grew up with an absent and selfish mother will also devote her time to her own social and love lives and claim that, "If you don't take care of yourself, you can't take care of your children." The idea of parental sacrifice is either taken to extremes (Ever met that mother/martyr who refuses to let her husband help her with anything?) or ignored altogether under the guise of not becoming a martyr. Our mothers fought for the right to be mothers and career women, to have it all. And now a lot of women have to fight just to get it all done, and the children get spoiled, either by being given too much stuff or too much time. If your kid grows up learning that every slight, real or imagined, is worth Mom marching to the school to fight over, or that every sniffle is worth a trip to the doctor's office, they develop a sense of entitlement. They should never feel less than 100% and a doctor needs to fix it now. The school can't do anything less than beneficial for them and the policy and/or curriculum needs to be changed now. This translates later to the fry cook who demands more respect at work even though he has the lowliest and least respected job in the place. He's not going to work his way up to a job that gets more respect; he's just going to demand more respect and a cost of living raise where he is. I once heard a fry cook, after two weeks on the job, complain when he got fired for excessive absences: "I thought this was supposed to be a company that cared about its employees and here they are firing me for being sick."
Our kids (collectively as a generation) and we, to a similar extent, are spoiled and fat and I think the two are very closely related. Our grandparents ate turnips and could make one chicken last 3 meals. I'm not suggesting we return to that, but daily cookies and soda, and portions as large as our plates are completely unnecessary. As is demanding respect and concessions from everybody at every turn. I heard a great quote once. It said "You are special and unique, just like everyone else."