Are there any negative side effects with the mass gainer " mutant mass" and if so can it affect my sperm?

Not studied. I just looked at the ingredient list of mutant mass and there is enough stuff in it that if you have any hesitation i would not take it. If it has not been fda tested it is hard to tell you it is safe. Build muscle the old fashioned way. Go to the gym and lift weights. Add more protein in the diet. Some of those body builders look like mutants with a lot of mass ha ha ha.