I would suspect part of it is because kids are having kids and because both parents are expected to be working to make due. Therefore, we don't have mom raising the kids all day, they are instead at child care through age five. Studies have shown our personalities are all but developed by age five.
When you have people having kids who are too young to learn how to adult themselves, I suspect that would contribute to some people growing up without morals, accountability and respect for others as well as a lack of self-awareness.
Here are some numbers about crime rate.
https://www.disastercenter.com/crime/uscrime.htm
Kevin makes some great points here. Children who grow up in families who are ill-equipped to raise them are much more likely to be involved in crime.
When we look at the numbers, crime rates have halved since peaking in the early 1990s and are lower than they were in the 1970s.
You have to go back to the 1960s to see years in which per-capita crime rates were lower than they have been in the last 10 years. And 1960s crime figures are problematic because if you look at murders, they were committed at a similar rate compared to modern times, however, the rate of reported rape was much lower in the 60's. Are we becoming a society of crazed rapists? Most likely not, it's simply much more common for rapes to be reported, as well as domestic violence and other crimes against women that were historically underreported due to fear of retribution, stigmatization, etc. And in the last few years rapes against men have been included in the statistics, resulting in a notable jump in those figures.
https://law.stanford.edu/publications/the-impact-of-legalized-abortion-on-crime-over-the-last-two-decades/ - the summary:
Donohue and Levitt (2001) presented evidence that the legalization of abortion in the early 1970s played an important role in the crime drop of the 1990s. That paper concluded with a strong out-of-sample prediction regarding the next two decades: “When a steady state is reached roughly twenty years from now, the impact of abortion will be roughly twice as great as the impact felt so far. Our results suggest that all else equal, legalized abortion will account for persistent declines of 1% a year in crime over the next two decades.” Estimating parallel specifications to the original paper, but using the seventeen years of data generated after that paper was written, we find strong support for the prediction and the broad hypothesis, while illuminating some previously unrecognized patterns of crime and arrests. We estimate that overall crime fell 17.5% from 1998 to 2014 due to legalized abortion— a decline of 1% per year. From 1991 to 2014, the violent and property crime rates each fell by 50%. Legalized abortion is estimated to have reduced violent crime by 47% and property crime by 33% over this period, and thus can explain most of the observed crime decline.
There are valid reasons to be against abortion but concerns over the rate of crime is not one of them. An outright ban on abortion would almost certainly result in increased rates of crime.
Here is my more general take on abortion:
It should be up to the woman, their family, and their doctor to assess the situation and make the decision.
In more extreme cases like incest and rape, requiring women to go through the trauma of not only being raped but carrying their rapist's baby to term and the life-long psychological side effects that will have on them is simply unconscionable in my view. Doubly so in cases involving children.
There are many cases where going through with a birth has a high likelihood of killing either or both the mother and child, and in these cases, it should be considered on an individual basis, and is not something an out-of-touch politician should be deciding.
In cases where there are bans on abortion, there need to be exceptions for rape, incest, and situations that pose a significant threat to the lives of mother and child.
This idea that abortion is used as a form of casual contraception is nothing more than a fantasy. Chances are someone you love has gone through an abortion and the very last thing it was was casual, easy, or poorly considered. In all likelihood, it was an extremely difficult and heart-wrenching decision to make.
At the end of the day, abortion is going to happen regardless of what the laws say so it should be performed by medical professionals and should be as safe as possible.