Causes of male infertility include:
-Using steroid- this causes the testicles to shrink thereby rendering the man infertile.
-Malnutrition and anaemia.
-Wearing tight pants and boxers- this causes infertility by decreasing the production of sperm due to the heat created by the tight underwear, this heat affects the scrotum negatively.
-Lots of intense workouts- Too much of high intense exercise is capable of rendering a man infertile as this causes the body to produce lots of adrenal steroid hormones, which then cause a testosterone deficiency.
-Smoking– this significantly decreases both sperm count and sperm cell motility, which is the ability to move spontaneously and actively.
-A prolonged use of marijuana and other recreational drugs.
-Chronic alcohol abuse.
-Lack of adequate vitamin C and Zinc in the diet.
The above show that male infertility depends a lot on health, so, men who live a healthy lifestyle are more likely to produce healthy sperm, thereby their reducing chances of infertility.

Seen this thread on NL before.. anyways nice post OP

Are a Medical scientist?

Dotwillis1:
Are a Medical scientist?

No,a computer scientist that's concerned about his health

Op, also add STD that are not treated well... It causes madness too...