Hmm, did not know that the exercise stew would work, nor the adults "entertaining" the kids! I shall have to get started right away

I have a beloved woman now over 50 who only birthed one child

And I'm really particular with the "stud" method. I tend to only do so with the ones who were paired together before because they tend to take better instead of constantly running away. And unfortunately, her man was about 10 years older and died before I purchased Med Tech Level 2.
So I guess you could say I base mine on affections or skill level. For example, I get some villagers who will take to anything in half the time! I've got one right now on her way to being an EE because I don' even have to check a preference and whatever I put her to do even once is what she sticks with! I also tend to use my runners, in hopes of making them skilled in all five. However, I do not let them waste too many years on kids since the running trait isn't inherited anyways.