Many people i know were born may or june, suggesting conception during summer holidays perhaps. Barely any i know were november birthdays.

I wonder if people put strategy into it - for instance you might think a september birth willl be better at school than their younger peers.

Or if age doesn’t affect school performance that much, they might feel bad if they underperform against younger students

Or perhaps you’d choose to create a summer child so they get to have finished school and uni earlier on in their life.