It's known that when children are born, they have a clean slate, meaning they don't know right from wrong. When I was taking early childhood classes, one of the few things I remember from class was a famous developmental psychologist named Jean Piaget who believed that children followed the morality of mainly their family before they hit 10 years old. Once a child hits 10 years old, they develop their own conscience and begin forming their own opinions and making their own decisions. With that being said, in this film, since all three of the children were born during the eclipse, they don't have that luxury where they know what's right from wrong. Therefore, these three kids go on a killing spree.
I really enjoyed this movie & it's so rare to come across slashers like these. I recommend this to all, definitely a good watch!