Example from Isola:

If I cross a fourpetal plant with a jalapa-flowered plant, I get hybrid seeds that grow into plants with fragrant flowers.

Genetic interpretation: Maybe fourpetal and jalapa are co-dominant and therefore their combination causes the fragrant phenotype, which is different from the parents. So let’s call the gene locus for flower types “A” and assume that fourpetal is caused by allele A1 while jalapa is caused by allele A2. Every plant has two alleles of the gene (one from the mother plant, one from the father plant) and A1A1 is a fourpetal plant, A2A2 is a jalapa plant, and interestingly A1A2 is a fragrant plant (due to co-dominance of the two alleles).

The cross is:
A1A1 x A2A2

All F1 hybrids are A1A2 and all are fragrant. This still makes sense.

The problem is the F2 generation. When I take the fragrant F1 plants and self-pollinate them, Mendel’s law of segregation predicts that I should get:

F1: A1A2 x A1A2 =
F2: 0.25% A1A1 + 0.5% A1A2 + 0.25% A2A2

So there should be fourpetal, fragrant, and jalapa flowers in a 1:2:1 ratio.

But all I get on Isola are fragrant flowers in the F2 generation. How?

I assume what happens on Isola is the following:
Parents: A1A1 x A2A2
Hybrids (F1, F2,…): A3A3

The two alleles of the parents blend together to form something new (A1+A2=A3) that wasn’t there before and there is no way to recover the original alleles from the hybrid plant.

This is completely contradictory to what Mendel found. He saw that the characteristics of the parents in a cross will segregate in the F2 generation. This doesn’t happen on Isola at all. I’ve never seen anything segregating in these plants. (And as a genetics teacher, I was a little disappointed by that.) They just blend together to form new species and all the seeds you get from that new plant then grow into more of the same new species. Back-crosses (e.g. A3xA1 or A3xA2) don’t work either. They give you yet new species of plants again (A4, A5 etc).

So Isola appears to be a fantasy world based on a Victorian era idea of genetics where the parents’ genes blend together to form new genes, and where Mendel’s rules do not apply. It’s still a fun puzzle game, but it has nothing to do with modern genetics at all and won’t teach you anything useful for biology class in that regard. In the real world, traits might blend, but alleles never do and the evidence for that is in the F2 generation producing parental phenotypes again. The genetics of Isola don’t work that way.

thank you