Making heir(s) for the family

Recently, you lost your father. To your surprise, a man turned up during his funeral and introduced himself as your grandfather. According to him, your father cut his family ties and ran off to marry your mother. However, despite your grandfather's efforts to explain to your father that the family wasn't against him marrying your mother, your father insisted on not wanting to have anything to do with his family. The only reason your grandfather chose to appear now was that he promised to stay away while your father was still alive.

His story was corroborated by your mother, who said that she had tried to get your father to reconcile with his family numerous times, but your father was a stubborn man.

Your grandfather then invited your family to stay with him, and your mother accepted. It was then you realized what was happening: your grandfather was trying to train you as his heir. He also told you to start making babies.

You protested, saying that you were just a young guy. However, to him, the excuse that you're young wasn't young enough to knock up a girl or a woman. Once you get her (them?) pregnant, the family will take care of it. He doesn't care with whom you do it, as long as you get the job done.

This is your story.

(For A heir to an old Japanese family, anyone interested is free to add his/her own branches, just as long the story remains consistent, i.e. the name used to refer to a particular people doesn't change, or the blonde mature lady in the earlier chapter suddenly becomes black hair teenager)