This is an interesting news story about one case of a "natural experiment" on human beings that would be quite unethical to perform on a large scale. The study of twins reared apart, which was especially active at my alma mater university while I was a student there,[1] took advantage of some other happenstance separations of monozygotic ("identical") twins into more than one family of upbringing to see what effects of home environment on genetically identical young people as they grow up might be.

For behavior genetic studies on fruit flies, direct gene manipulation is considered ethical, and quite harsh environmental tests, tests that would never be considered ethical for mice, are also used. For mice, they can be bred into inbred strains in which every individual for generation after generation is all but identical, and can also be given gene "knockouts" through genetic engineering technology, and the environments can be varied by systematic controlled experiments rather than the haphazardly varying experiences of human beings.

I discuss issues related to this research every week during the school year at my alma mater university with some of the world's leading experts on human behavior genetics.[2] This is a fascinating area of research, and there is always more to learn. Some of the more puzzling questions will probably only get answers as more researchers from varied postgraduate educational background collaborate on conducting continued research.

[1] http://www.hup.harvard.edu/catalog.php?isbn=9780674055469

[2] http://www.psych.umn.edu/research/areas/pib/