This question already has an answer here:
According to this article
your intelligence as an adult is to 80 % determined by genetics:
Despite the well-known difference in twin-based heritability for intelligence in childhood (0.45) and adulthood (0.80),
If you are born with a strong predisposition for limited cognitive abilities, can you do something to improve the situation?
Compare with more physical traits. To win a medal in the Olympic Games you probably need to have an outstanding predisposition for that specific sport BUT unless you have a very negative predisposition for something (such a limping and trying to be a marathon runner) you can by hard work become a "good amateur", probably ending up in the top 10 %, and maybe even top 1 % or so, "just" by a lot of work. (However, top 1 % won't give you any medal on most regional or national championship so you are still a loooong way from the olympics).
It is obvious what you need to do to achieve that: play a lot of tennis (if tennis is the sport you want to be a good amateur in) combined with some more generic weight and fitness training.
Can you achieve similar results (top 1-10 %) with regards to your cognitive abilities with hard work? Why? Why not? How?