You can see the list of criteria here: https://www.faa.gov/air-traffic-controller-qualifications
Education isn't just about changing the quantity of knowledge people have learned - a country with good free education, along with other things like mental health support, good parenting resources/education/support, etc. will lead to more people having the qualities needed to be ATCs despite not having learned them by going to specific "managing stress 101" classes.
(Edit: It's possible I misunderstood you and by innate qualities you literally just meant the things in their explicit requirements list like being under 31 and being a US citizen, if so apologies but I'll leave my comment here anyway.)
- Be under the age of 31
Well, they restrict the pool pretty harshly right from the start.