Ali jan, rabtesh ine ke, you cant have absolute certainty when it comes to parenthood, you yourself say even with condoms you would never know when they are 99% effective. Your whole issue with this was you wouldnt know who the father is, im telling you, you cant tell 100% either way without testing.
They do not need condoms, a woman can tell when she is ovulating by counting the days, its the oldest form of contraceptive known to man.
btw, condoms were widely available in Iran for anyone interested last time i was there.