Behaviour is usually an uncountable noun, so it is rarely used in the plural:
✗ Parents should be able to prevent their children’s crimes or bad behaviours.
✓ Parents should be able to prevent their children’s crimes or bad behaviour.
✗ The media often encourage violence and aggressive behaviours.
✓ The media often encourage violence and aggressive behaviour.
The plural form ‘behaviours’ is a specialized term used in fields such as psychology, social science, and education. This use is much less common than the uncountable use:
In this chapter, we discuss strategies for dealing with the problem behaviours of young children.