People respond differently to anabolic steroids. Some men's libido and erection frequency will increase, while in other's it may decrease...even to the point of impotency. During a cycle, the effect can go either way, however, post cycle, is usually when a lack in sexual interest is seen, and in extreme cases, the inability to achieve an erection. This is because when steroid therapy is discontinued, you are often left with little natural testosterone in the body due to suppression of your own production. However, with the proper use of drugs like clomid, nolvadex, and HCG post cycle, these sexual effects are mostly temporary(except in extreme cases)and with time, your normal testicular/sexual function will return. So when you are off steroids you should not have a problem fathering a child.