It does happen rarely, but only rarely. Typically we're done growing around 16 to 18, sometimes even earlier. All you can do is just watch and measure to see if there is any progress.
If you're not growing, you could always travel to Russia for that height increasing surgery, but I warn you it is painful. They do a series of controlled fractures on your legs, and as the bone heals, the leg bones get longer. Results as much as 18cm have been achieved with this procedure, though you do have to go to Russia to get it.
Most guys still grow physically until their early twenties and some of them do grow height and some rare cases get a real growth spurt so it's definitely possible. I've even seen it happen. And yes you could have growth genes from your grandparents since I do too.