I also think that the meaning of bad (or good) is not simple. These are qualifications that do not exist on their own, in nature, they are created and experienced by humans. So, subjective by definition.

I believe in genetics and other biological mechanisms. It is a well known fact that some genetic backgrounds can predispose people to aggressive, antisocial, violent behaviors. As such, we can say that some babies are born with a tendency to be "bad" and it may or may not manifest later. Of course environment and experience can modify the function of our genetic material dramatically but DNA, and a few other biological features that are established prenatally, are things we are born with.

I personally don't tend to be moved by babies at all, they don't invoke in me any strong association of innocence or tender feelings (that's just me, I also never wanted kids). What is innocence actually? Not breaking the law is the easiest definition, and of course babies are then innocent.

It's more that they have not yet had the life to demonstrate lots of actions. I also think that they can be more selfish than many adults as they are primarily creatures of instinct and very basic needs and have not yet learned self-control and other forms of complex social interaction. Of course they cannot be violent easily since they don't have the physical capabilities or language/complex emotional behavior to be abusive. But babies can be more ruthlessly needy than even an older infant (who already developed some control), it is simply a need to survive and have basic functions and comfort fulfilled.