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There are definitely things like dominant and recessive traits- it's just that only a limited number of genes actually demonstrate this behavior in a non-ambigu

by dekhn 2y ago

There are definitely things like dominant and recessive traits- it's just that only a limited number of genes actually demonstrate this behavior in a non-ambiguous way. Eye color and hair color have been studies pretty intensively and they definitely have models which are more complex than "if you have value Y at position 37 of gene X, you have blue eyes". The way it's normally stated is that we can explain 50% of the heritance of eye color using a limited set of SNPs. What we don't have is a comprehensive model of how complex phenotypes arise from genotypes. This is only because of historical oversimplification, and partly because the underlying causality of phenotypes is remarkably sophisticated due to a combination of many factors, overlapped with enormous amounts of noise and confounding factors.

oldgradstudent 2y ago
> Eye color and hair color have been studies pretty intensively and they definitely have models which are more complex than "if you have value Y at position 37 of gene X, you have blue eyes". The way it's normally stated is that we can explain 50% of the heritance of eye color using a limited set of SNPs. That's all very nice, but can you predict eye color from a genetic test with reasonable confidence? That a very simple question and the answer is apparently a resounding no.
- dekhn 2y ago
  I think the answer is, "yes, we can predict eye color from a genetic test" but the prediction will be probabilistic and frequently wrong. For example: https://www.ancestry.com/c/traits-learning-hub/eye-color https://www.ancestry.com/c/traits-learning-hub/eye-color and the references suggest such a test exists.
- robwwilliams 2y ago
  Definitely NOT a resounding no. Here are two recent studies that might be of interest. https://pubmed.ncbi.nlm.nih.gov/32488945/ https://pubmed.ncbi.nlm.nih.gov/32488945/ https://www.science.org/doi/10.1126/sciadv.abd1239 https://www.science.org/doi/10.1126/sciadv.abd1239 The second study demonstrates that more than 50% of variance in eye pigmentation can be explained by simple additive effects. “ We identify 124 independent associations arising from 61 discrete genomic regions, including 50 previously unidentified. We find evidence for genes involved in melanin pigmentation, but we also find associations with genes involved in iris morphology and structure. Further analyses in 1636 Asian participants from two populations suggest that iris pigmentation variation in Asians is genetically similar to Europeans, albeit with smaller effect sizes. Our findings collectively explain 53.2% (95% confidence interval, 45.4 to 61.0%) of eye color variation using common single-nucleotide polymorphisms.” Hardly a resounding no.

by dekhn 2y ago

oldgradstudent 2y ago

> Eye color and hair color have been studies pretty intensively and they definitely have models which are more complex than "if you have value Y at position 37 of gene X, you have blue eyes". The way it's normally stated is that we can explain 50% of the heritance of eye color using a limited set of SNPs. That's all very nice, but can you predict eye color from a genetic test with reasonable confidence? That a very simple question and the answer is apparently a resounding no.

dekhn 2y ago
I think the answer is, "yes, we can predict eye color from a genetic test" but the prediction will be probabilistic and frequently wrong. For example: https://www.ancestry.com/c/traits-learning-hub/eye-color https://www.ancestry.com/c/traits-learning-hub/eye-color and the references suggest such a test exists.
robwwilliams 2y ago
Definitely NOT a resounding no. Here are two recent studies that might be of interest. https://pubmed.ncbi.nlm.nih.gov/32488945/ https://pubmed.ncbi.nlm.nih.gov/32488945/ https://www.science.org/doi/10.1126/sciadv.abd1239 https://www.science.org/doi/10.1126/sciadv.abd1239 The second study demonstrates that more than 50% of variance in eye pigmentation can be explained by simple additive effects. “ We identify 124 independent associations arising from 61 discrete genomic regions, including 50 previously unidentified. We find evidence for genes involved in melanin pigmentation, but we also find associations with genes involved in iris morphology and structure. Further analyses in 1636 Asian participants from two populations suggest that iris pigmentation variation in Asians is genetically similar to Europeans, albeit with smaller effect sizes. Our findings collectively explain 53.2% (95% confidence interval, 45.4 to 61.0%) of eye color variation using common single-nucleotide polymorphisms.” Hardly a resounding no.