How to make babies and find true love with a tavern wench.
The first thing you'll want to do is level up far enough that you become a citizen.
You are then granted the freedom to start a love affair with up to three women as far as I can tell. Maybe more.
The option to do this is under "Social Activities" when you click on your main character.
Note: You cannot woo and betroth your employees. I tried to do this as they're reliably easy to locate, unlike some of my love-connections, so something to keep in mind is that you'll need to be able to find your lover. If their daily path crosses your home's front door, grab them.
In order to really get what you want (an heir) you'll need to be able to propose to your lover.
You need to level up the "Enchanting" perk which requires 1500 XP and is near the bottom of the skill list, or you may (unconfirmed) need to be their lover for several seasons if not years. I bee-lined for "Enchanting" because I did not believe that waiting was the correct answer. Less than a minute after I completed Enchanting, I was able to propose.
The next step is proposing. Hold your breath, click propose, and she'll accept.
In order to get an heir, stick your wife in your house. She cannot as far as I understand be used as a mule to gather resources and sell items. She basically has no reason to leave the house after marriage.
Spend time crafting in your house.
After around a year of being married, you should produce an heir!
My little boy is gaining experience in the crib while I continue to try to figure out how to create one of those hand-cart contraptions, so the guide wraps up here.