A Look at Genetics in The Sims 3

Case Study 3: Breaking the Family Tree

The Rumbaa Family – Genesis Rumbaa - 2nd Generation

Genesis and his wife Angelica live in Roaring Heights. Nathaniel and Trinity, Genesis’s parents’ live in Moonlight Falls while Francesco and Alexandria, Angelica’s parents’ and younger brother Keanu are currently in the library waiting for the next round to be moved into Roaring Heights. Currently they are both disconnected from the 1st Generation. When the family tree is intact and all are in the same neighborhood I know there is a chance for a grandchild to inherit a grandparent’s hair/eye color, but what happens when the grandparents are not present because you move the 2nd Generation to a different neighborhood, thus breaking the family tree?



There are two methods which lead to the same results.

Method 1: CAH (Create-a-Household)

I used NRass to take Genesis and Angelica into Stylist to save them to the CAS bin then exited out to enter CAH in Edit Town. Once in CAH I opened up the saved Sims bin to retrieve the two Sims and then proceeded to Play with Genetics. The children came out with black being the most common, blonde and orange hair. There was no preset brown among the genetic calculator which is Genesis’s father hair color.
So to answer the question I posed to better understand the implications of my chosen playstyle, the answer is: The game appears to be coded in a way that grandparents must be present in the same neighborhood in order for there to be a possibility of a grandchild to inherit their hair/eye color. The grandparent’s dominant genes become non-existent and no longer included in the gene pool with any family unit who is disconnected.


Method 2: Instant Baby (NRass Master Controller)

As mentioned before, this replicates the same results as method 1 and this can be taxing and crash the game. I tend to get more stable results when I keep the game on pause when I do this. However, I would not recommend this method.


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Recessive Genes

To refresh, recessive genes are those that one is a carrier of but does not have, but can pass the gene(s) down to their child either as a carrier or inheritor.
The grandparents’ hair/eye color will not have a chance to get passed down to descendants when the family tree becomes incomplete, however, their recessive genes do which seem to imply the game is coded to specifically use the hidden assigned recessive gene(s) in addition to inheriting grandparents’ hair/eye color when the family tree is intact. Otherwise, when the family tree becomes fragmentary, only the recessive genes will continue through the generations regardless of the condition of the family tree.

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The 1st Generation Recessive Hair Colors

Trinity and Nathaniel produced children with Black, Blonde, Brown and Orange hair. Francesco and Alexandria produced children with Black, Blonde and Orange hair. In order to attempt to get the Punnett Square accurate, I have to use trial and error based on in-game data, but there is still quite a bit of guesswork. Meaning I know which couple has which recessive hair/eye colors, be that as it may, there is no known way of pinpointing which recessive hair/eye color is whose. All I know for certain, is both Blonde and Orange are the known recessive hair colors that can be passed down to the 2nd generation and so on.

Nathaniel and Trinity Recessive Genes
https://i.postimg.cc/xT9t3rMn/Rumbaa-Recessive-Hair-Color-Blonde.png
https://i.postimg.cc/Dw4hnbZC/Screenshot-1422.jpg
https://i.postimg.cc/9FXYqdHf/Rumbaa-Recessive-Hair-Color-Orange.png
https://i.postimg.cc/fRgRzNDK/Screenshot-1423.jpg

Francesco and Alexandria Recessive Genes
https://i.postimg.cc/0QBLRMcP/Recessive-Hair-Color-Blonde.png
(Oh and I discovered that Francesco and/or Alexandria, is a carrier for grey eyes.)
https://i.postimg.cc/C56D4Yhv/Screenshot-1420.jpg
https://i.postimg.cc/rw7BPtZT/Recessive-Hair-Color-Orange.png
https://i.postimg.cc/MK321Lyv/Screenshot-1421.jpg


Certain genes get turned on or expressed while the rest is turned off or unexpressed. Basically when the genetic calculator chooses between the father’s or mother’s or grandfather’s or grandmother’s or recessive hair/eye color for the offspring. So many possibilities can carry different genetic information that can result in similar looking siblings to siblings who look nothing like each other to descendants with an unexpressed hair/eye color from a previous generation.

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The Possible Genotypes and Phenotypes of Genesis and Angelica

(Now I know the game is not coded to count the grandparents hair/eye color as recessive, but will have the extra genetic information to choose from when considering the phenotype of connected families. I will have to revise the Punnett Squares to reflect this new discovery.)


(However, since I cannot figure out for certain which recessive gene is whose in some or most cases, then I will carry on in a different approach without the Punnett Square. For example, when one or both Sim(s) is/are known to have more than one recessive gene for hair/eye color then it gets especially complicated not being able to know for certain which Sim has what. It would have been nice to have options, thus control over recessive genes being chosen by the player using CASt to pick or create any color besides an option to choose randomly from the CAS hidden presets. Also, that up to 3 different variations of the same hair/eye color could also be incorporated such as one parent having 3 different shades of blonde hair and 2 different shades green eyes or none at all and another parent having different 2 different shades of brown hair and 3 different shades of grey eyes. And of course, on top of that, up to 3 different recessive hair/eye colors. That seems to be the case in TS3 but just not player controllable unfortunately.)