Here's an answer from my point of view:
-Normally what we do now is a reflection of our parents' actions or lessons they taught us. Similar to us, the way the mother and father of the parents may have raised their children may result in how they lead their kids. For instance, if someone's parents did drugs or bad things, their children may adopt those habits. The future kids of those children will then adopt those habits since their parents didn't teach them what's right or wrong. Overall, it's a cycle of not setting good examples and/or not teaching children properly which leads to the future generation not being raised well either.
-Another example is really simple: mental health issues. These problems can arise at any age no matter what kind of a lifestyle you have. An example is if someone witnesses something horrific, like a person getting beat up in front of them. This may result in paranoia or anxiety which can lead up to a person spiraling into madness and cause someone to obsess over violence. If this person has a child, they could teach their child to be violent or they could be violent with their child. Of course, this is just an example. There are many more possibilities as the human mind has no limits.
-Since technology has evolved, this can be an influencing factor in personality and actions. Lots of people might've heard of the Facebook moms since they just listen to everything they find on that social media platform. That's a great example on how technology influences choices. When online, people could get influenced by lots of topics, parenting included. Often times, people tend to listen to people they don't know since its an outside opinion or something new that seems fun. Like on Instagram reels, parents paint their children's toys to meet their own aesthetic, a plain beige color. Of course it isn't healthy for a child since they're supposed to be extremely happy at that age and have cool colorful toys surrounding them. The more vibrant the color, the more fun! However, the unfortunate reality is that people tend to be selfish and are easily influenced by bad things and they don't even realize.
-Sometimes, the parents do lead their kids down the right path, but the process is too harsh for a child. Like commonly in Asian families, parents try too hard to push their kids to become doctors or lawyers. In my opinion, children should have fun in their childhoods so they don't increasingly crave stuff they never got to experience because their parents desperately want them to fulfill the dreams they never got to achieve. Obviously if pushed too much, the child will become discouraged and disobedient so gently guiding children is crucial in leading them to the right path. This is a very common situation especially when adults want their children to chase their old dreams (the parents' dreams) and not have any goals of their own (the children).
In summary, these are some factors as to why many parents cannot lead their children properly. Even if they did, there are also many outside factors as to why children nowadays don't go down the right path. Factors such as peer pressure and social media is now a big issue in the behaviour of people. So in conclusion, parents are NOT the only problem when children go in the wrong path. Do not blame them for something they cannot control.