In your culture the best thing to do is maybe talk with your dad about it or perhaps some of the elders where you live.
There could be some expectations that boys wear the vest when they reach a certain age and if they don’t it could be considered disrespectful or offensive.
If there are no religious issues or any other concerns that will upset your family or others the choice should be yours whether to wear the vest or not.
You have to keep in mind that in a culture like yours that has many traditions dating back centuries going against what is expected is often not well received.
I would think it would be just what you’re exposed to if most people wear vests then many people continue the same trends.
In many places baseball caps are worn by the majority of kids it is just a trend that many like to follow.
Fashion trends and styles can change and for many kids the latest fashion trends are what they feel they need to have to fit in.
The wearing of vests in your country seems to be something that has been a mainstay for generations and would probably be considered as traditional dress.
The wearing of vests in other places is something that has just never been a popular clothing item.
In places where farming and ranching are part of daily life for many the dress tends to take on a western wear style of clothing. There can also be a difference in what is worn between people who live in the city and those who live in the country.
It often just comes down to what is practical and popular where you live.