The first guy’s email who called the genetics study “silly” responds to the other guy who said he was wrong. Got that? Good:

In response to my email you posted earlier Jonah, one of your other readers argued that parents’ partisanship shouldn’t have much, if any effect on genetic transmission of political ideology/policy preferences. This is of course a very weird argument logically, because if political preferences are transmitted genetically, then parents have everything to do with that genetic transmission and so partisanship does matter. In fact, that is something you would really want to know if it is possible to transmit preferences genetically. But on top of that, it is important to know it for at least one other very important reason. How do we know the differences we are seeing between identicals and fraternals is due to genetic transmission of policy preferences and not simply the intergenerational transmission of policy preferences, partisanship and ideology we know occurs from parents to children after they have been born?
For starters, we would need to know if the parents in each group (fraternal and identical twins) were about even in terms of their ability to transmit ideology. What determines that? A number of factors do, but one of the strongest as I said in my first email, was whether the parents are partisans themselves. Are they strong or weak partisans, and do they match in their partisanship? Children from families with parents who identify strongly with the same party are more likely to take on that party id. If your two groups are uneven in this regard (the parents I mean) then high levels of differentiation among fraternal twins or high levels of matching preferences among identical twins, could be due to this factor and not a genetic predisposition to a particular policy preference. In other words, if you have more unmatched partisans or non-partisans in the sample with fraternal twins, you may see more differentiation among these twins in policy preferences than in the other sample with identical twins because the transmission of core values and partisanship would likely be weaker. Thus, the argument that it is genetics would be less persuasive than a simpler argument that the intergenerational transmission is much weaker in the fraternal group. Likewise, if your sample of identical twins has more families with parents who are partisans and do match, then you could again make a similar argument without accounting for the much stronger influence of intergenerational transmission in the identical twin group.
Finally, the point I was trying to make about whether fraternal twins are genetically predisposed to differentiate more than identicals was not a moot one. If the genetics of a particular family member – let’s say the dad- are responsible for a particular policy preference or general attitude toward this kind of policy, and dad’s twins get that genetic package, the logic of the study would be that if dad’s twins are fraternal, they will be less likely to match each other than if they were identical twins. The burden of proof however, is whether this is because identical twins share 100% of their genetic material and fraternal twins half, or whether because of this, fraternal twins are more likely to differentiate attitudinally in the first place because they do not want to be identical and that kind of behavior is socially less reinforced on fraternals than on identicals. If there is a genetic determinant of political preferences in this case, it would be that fraternals are more likely than identicals to try to differentiate themselves from each other- not that because they are genetically differentiated then any differences between their political preferences can be chalked up to these differences.
Anyway, just wanted to defend my honor on that score.