I've had 3 families with total incompatibility recently, and one a week or so ago. It annoys me to no end! 7 or 8 gens all with 6 kids each and then BAH! My streak ruined. lol

I was actually going to make a post about incompatibility soon - I was waiting for three more gens to end. I've been studying desire for children, number of kids and happiness level. So far, desire for kids has nothing to do with how many they can or will have and all of them (regardless of whether or not they want kids) get a bit happier when they have a child (as most of us had already figured out.)

For eight families, I had exact matches for desire for kids (both "No Way" or both "Definitely" etc.) One of these is one that I call "incompatible." They gave me fits having children - both were Maybe. Between the second and third child, they had two failed attempts. MD consults were clean. I began boosting prior to every attempt. After two doses and attempts, they had a third child. After NINE MORE doses and attempts, still no more children. There was nothing in the likes or dislikes to give any clue to incompatibility (only one like for pasta.) The seven others had 5 or 6 kids each. (The two No Ways had six.)

For four families I had a No Way and a Definitely: three of them maxed out at six kids; one had an illness that delayed us, but they still managed five children.

All the others were a mixture of desire for kids. Results were basically the same, with an average of 5 kids. Most had some failed attempts as they got older, but it was immediately "cured" with baby boost.

2 of these mixture families were also "incompatible." One of them needed baby boost prior to the first attempt (I do consults on all new gens) but the others had no fertility issues. The only consistency I see is the incompatibility. Meaning, they just fail and fail and fail.

When I have two failed attempts in a row, I boost prior to the next attempt and continue that until they have success. These "incompatible" couples cost a fortune in baby boost (one of my study families was only second gen and just my luck, they turned out to be incompatible.) I managed to get 5 kids from one of them, but literally ran out of space on the family tree notes to record how many times they had been boosted and failed.

My conclusion so far: incompatibility is random, but definitely does happen. It's highly annoying. There is no way (that I have found) to predict which couples will be incompatible.

The solution: Keep boosting prior to attempts (if you can afford it) and most importantly, just keep trying (every 20-45 minutes, depending upon their desire for kids / how soon they will try again.) As always, if you have a couple that has reached 40 and still has no kids, pause the game and make a backup copy of that family file so you can reload it and start from there again in the event they fail to have any kids and don't get to adopt. Try not to take it out on the poor lil peeps. They ARE trying, they just aren't lucky. (That part's for me because at one point I really wanted to punish one of my lil females for not having a kid. lol)