Is flirting supposed to be natural or an acquired ability?

I am a 23 year old guy, I'm self-assured, confident, intelligent, randomly funny but I don't seem to know how to properly flirt with people at the right time, it seems to me like a very hard thing for me to do.



My case:



I feel sometimes that Girls do find me attractive and sometimes not. When im interested in a person I usually act myself (like as in I cannot tell(unsure) whether or not I am flirting)



The reason i asked this question is because I find very hard even at University. Also I don't really understand how to flirt with girls in high school (back then when all it is just, study, work and play..) I find that lots of guys are able to go out with girls on dates back in high school even in primary schools.



I want to know if this kind of ability is something you build up as you grow older, from parents or something everyone acquires from the time that person is born or something else?Is flirting supposed to be natural or an acquired ability?
You probably flirt all the time and don't really noticeIs flirting supposed to be natural or an acquired ability?
it's usually very easy... and naturall!