Children only misbehave if their parents are bad?
Physical punishment may be the best recourse even if it isn't the only.
It is within a child's nature to explore, learn new things, and imitate its parents. There is no natural tendency in children to do anything other than that.
Of course, you ask a tough question and the answer depends greatly upon what constitutes "misbehaving".
To some parents, an infant or toddler crying because it is hungry and wants to you to get off your butt for just a second to feed it, constitutes "misbehaving."
To some parents, a child who is often not payed attention to --- because the parent would much rather watch television, go out drinking, or is more in love with his/her job --- and then acts out due to that lack of attention, is claimed to be "misbehaving."
To some parents, when a child decides to copy the acts of the adults around them, most specifically the parents, and these acts are profane or lewd, the parents describe that as "misbehaving."
"Do as I say, not as I do." Sorry jack-off, your children have an almost irresistible urge to copy everything that you do. You, as a parent, should know this. They WILL copy everything you do. If you don't want them to do it, stop doing it yourself. Your job is to teach your children how to live and your children learn almost exclusively by example, rather than by your decree.
Your children are not an accessory, either. There are a great responsibility. You have to actually pay attention to your children and teach them stuff worthwhile. You have to provide a good example to them. You CANNOT allow television, video games, and other people raise your children. If you do and they "misbehave", then YOU'RE at fault.
So, no. In my opinion, physical punishment is not the best recourse. Physical violence occurs when one or more parties to an event lose control of the situation. Children who've had violence done to them by parents lose trust and the feeling of security and safety with their parents. They become less out-going and more introverted. And the violence never solves the root of the problem, though it may terrify your children into silence and submission for the moment.