By default behaviors  are not copied to new agents, but you can change that easily by calling
auto* gd_behavior = new GrowthDivision();
my_agent creates another agent (e.g. through cell division) a copy of
gd_behavior will be added to the new agent.
If you want that a behavior is only copied for a specific event (and not for others), have a look at the function
PS The same principles apply for removing a behavior from an agent (
 BioDynaMo: bdm::Behavior Class Reference