Yeah this paper came across to me basically as "if you ignore environmental causes of death, the heritability of death goes up"... which seems kind of circular.

Not necessarily. It could be the case that randomness plays a huge part in non-environmental caused deaths, and if that were the case we would see very little heritability.

I really like everything Uri Alon (last author) publishes, but these types of studies have a history of inflating genetic contributions to phenotypes. Decoupling genetics from environment is not easy as they are both highly correlated.

In fact, the article discussion states: "Limitations of this study include reliance on assumptions of the twin design, such as the equal environment assumption". My take on this is that the main result of the article is probably true, but the 50% figure is likely to be inflated.

There's no prior reason to expect the cited conditions to have any specific relation to genetics. Any of them could easily be caused or accelerated by environmental conditions.

And, in fact, it looks like they half-of-are.

I thought the implication was lifestyle isn't as important as we previously believed.