IQ is mostly genetic. There is literally nothing we can do about it, as far as we currently know. Blame your parents if you wish.
I disagree with that notion. IQ is a statistical measure of rather arbitrary test results of tests that can be practiced for. If you really cared you could increase your IQ to 120~140ish by sheer effort. From that point onward we're so far to the right of the mean that no tests really exist in sufficient volume.
There is a difference between IQ and Intelligence. The frome being only an attempt to measure the latter.