If you were a woman, it could because drugs can damage eggs in women. Women are born with a set number of eggs, we don’t get new ones so if they are damaged, that’s pretty much it. That’s why alot of medications say don’t take this if you are pregnant or plan on becoming pregnant.

However, with men it isn’t exactly the same thing. Men do actually create new sperm on a daily basis. And the sperm that’s created is, in it’s early stages, extremely fragile and dies easily. So, the sperm you had during your drug using years is not the sperm you had when you and your wife/girlfriend whatever concieved your son. So while the drugs may have damaged the quality of the sperm at the time, it wouldn’t damage the quality of the sperm created later, once the drugs were out of your system.

Of course that doesn’t mean that there isn’t something going on in the genetic makeup of the sperm that’s causing his problems, however that wouldn’t be related to the drugs you took most likely because drugs like that don’t really alter or mutate the DNA in your body like radiation or certain other chemical agents might do.