A few months after birth or a year, seeing as twins can get so close within those few months and develop separation anxiety from their twin
I believe the answer is: <span> it is a strong predictor of later aggression in adolescence and adulthood
Children who display constant physical aggression toward others generally experience some sort of problem in their home (they are either being ignored by their parents or they witness their parents do it and imitate them).
If this left unhandled, the aggression would become a habit as they grow up and make it much harder to be changed.</span>
The theory which states that when there are multiple possible explanatons of an event or a phenomenon, the simplest is the best would be Occam's razor.
However, it's important to note that this idea actually states that we shouldn't necessarily multiply ontological entities, which doesn't really mean the easiest solution necessarily.
One of the advantages attributed to large population sizes