When you want a child:

Mate only those over 18, women who are under 50 and neither of them are sick.

Watch the Population indicator. It will increase IMMEDIATELY when a coupling results in a child. No need to wait for them to go inside to see if it "took". In that way you can drag one to the other over and over and over until you get a kid. While it may be true that some couples are more compatible, I've never failed to get a child from any combination of "eligible" villagers, unless the food supply is very low or the housing is inadequate.

Jer

There are two theories to arguing with women. Neither one works.