Sterile men?

Is it possible that some men are just a lot more fertile than others? Despite age or lifestyle? I had a past boyfriend who I never used protection with not once and nothing ever happened. My current partner & I have gotten pregnant very easily every time we’ve ever had unprotected sex during my fertile window. We had a miscarriage in the past and also a chemical. But Now I’m 6 months pregnant with baby boy 💙🙏🏼 but I am just wondering if mens fertility is different like that even though my past partner was almost 10 yrs younger than my current. And not particularly less healthy ? Maybe some men just don’t have strong swimmers? I just like to learn about things and find it interesting. Also I wasn’t sure which group to post this in so just put it here