A non-hormonal, reversible and non-toxic male birth control could be a step closer, with scientists successfully targeting a protein that's crucial in making fertile sperm. Knocking this protein out for a period of time would give men control over their protection window, much like oral contraceptives for women – but without other side effects and no long-lasting fertility issues.Scientists already knew that a serine/threonine kinase 33 (STK33) gene mutation results in the male being sterile. Wh...