Contrary to popular opinion, kunoichi are not always sent out to seduce powerful men and gain new secrets for Konoha. In fact, most of the female ninjas of Konoha are just as they appear: tough, strong, and capable fighters. They are not universally weaker than their male counterparts, as the great Lady Tsunade shows, and frequently destroy their male partners in one-on-one battles. For this reason females are usually placed against one another for fights. It is completely deliberate and a sad attempt by the commonly male Hokages or Council members to prevent demoralization among the males of Konoha.
Not every village is like Konoha, and some villages do allow their female ninjas to annihilate their male counterparts. Mist had this as a particular favorite method and the former leader was apparently convinced that a good ass-kicking would show the men how weak they really were.
About half the female population loved her, while the other half and almost the entire male group thought that she was a crazy Amazonian bitch.
She quietly lost power and a perfectly ordinary male, who had never faced off in single combat against any female in his life, replaced her.
This is not a particularly well known even in any of the villages except Mist and Konoha. The first Hokage was extremely aware of how strong female ninja were, but he was more interested in keeping a population of ninja rather than having a single generations of amazing fighters. For this reason, Konoha (and several others villages that will never admit to emulating the great city) keeps only one kunoichi on three man teams and usually secretly restricts academy entrance to one-half that of males. There's twice as many male ninja compared to female in order to keep a population going. If the whole group of females capable of becoming ninja were used, Konoha would have a dramatic population decrease within a single generation. Ninja have a generally shortened life expectancy, and rather frequently the females never have children. Males also often lack offspring.
Ninja are not universally passionate people and there are rarely children of mixed village heritage. Ninja are usually intelligent and they know that mixing with other villages can cause conflicts of loyalty, and avoid having children outside their own sphere of influence. When these children appear, there is no signed agreement, just a general understanding that these children belong where they are born. This practice is due to the fact that these children are almost always the result of one of those rare kunoichi trained to seduce other ninja. If the mission is long-term, then perhaps the child will be born in a waring village, but only of the mother chooses not to return hope before the birth. Fathers often have no idea about the birth, if the mother chooses to have the child, and orphanages in all villages have many "parentless" children who may actually have one or both of their progenitors living. Their fathers have no idea about their existence, and their mothers may be too valuable to remove from duty merely to care for an accident from a mission. These children are of course watched carefully and funneled into the ninja academy of their mother's village, well, only half if they are females.
Let us return from this digression to Konoha ninja.
The current generation is exceptionally odd in that all of the Rookie Nine, and three of the prior graduating class are related to these strange practices of kunoichi. The majority of their half-siblings that reside in Konoha are also current or future ninja, although not in the general population pool at this time.
Here are their stories.