A major issue in human genomics over the past few years has been the case of the “missing heritability“. Roughly, we know that for many traits, such as height, most of the variation in the trait within the population is controlled by variation in the genes of the population. The height of your parents is an extremely good predictor of your height in a developed nation. If you’re adopted, the height of your biological parents is an extremely good predictor of your height in a developed nation, not the height of your adoptive parents. Though a new paper claims to have resolved some of the difficulty, one of the major issues in human height genetics has been the lack of large effect quantitative trait locus. In plain English, a gene which can explain a lot of the variation in the trait. Rather, many have posited that continuous quantitative traits like height are controlled by variation in innumerable common genes of small effect size, or, by innumerable rare genes of large effect size. The same may be an issue with personality genetics, or so is claimed by a recent paper unable to find common variants (though an eminent geneticist pointed out in the comments some problems with the paper itself).
One would assume that the same problem would crop up across the tree of life. But a geneticist once told me that he considered biology the science where all rules have exceptions. Many exceptions. A new paper in PLoS Biology paints a fundamentally different picture of the genetic architecture of many morphological traits in the domestic dog, A Simple Genetic Architecture Underlies Morphological Variation in Dogs: