I smoked a shitload of weed for 20+ years. Then my wife and I decided it was time to have a baby. She stopped taking the pill, then I used condoms for 6 months (best to get the pill totally out of the system first). Then Bam! First time without a condom and she was pregnant. We know it was that time because I had been travelling on business right after that. So, unless it was the mailman's kid, it happened that one time. Seems that my sperm didn't have much of a problem

Anyhow, I had read that recent studies showed the damage to sperm from weed was negligable, if at all. No where's near what the govt would like us to believe. Tight underwear and hot tubs are most likley worse.