We haven't changed much of our DNA within a generation, it doesn't 'work' like that..
What has changed seems to be the amount of calories is too great for many people to remain of normal fatness leading to the metabolic syndrome. What might very well also have changed is that every calorie ingested from over processed food (of any type) has more likelihood of being absorbed and stored than foods in the more natural state. They also take less energy to process. And as Scandichic points out too many are sedentary
(yet I have to say my grandchildren and their friends seem to be very active, they climb, they belong to the scouts/cubs. They walk quite a long distance to school and the shops and they ride their bicycles. They are also all thin)
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Can we say what diet is best for Health, yes say the authors of this review; but it isn't a diet where one element is overly restricted or emphasised, it is one based on natural foods, and tends to have a foundation of plants (but not necessarily exclusively plants)
http://www.annualreviews.org/doi/full/10.1146/annurev-publhealth-032013-182351
Basically we have a bit of market research and a comment not a piece of academic research. That's the Daily Mail for you
What we don't know is what those Australians who identify with eating a low carb diet actually eat
They've done that in Finland and the majority actually ate quite a diverse diet including some grain (and some seemed to be only nominally low carb)
http://www.kuluttajatutkimuskeskus.fi/files/5852/Artikkeli_lowcarbohydrate_Jallinoja_2014.pdf
.The grain lobby will have undoubtedly have 'seeded' this article into the press with a nice bit of marketing. That of course also applies to other pressure groups. For example a piece of research suggesting sat fat was good also got good coverage in the press and on here recently. This was sponsored by egg, meat and dairy producers plus the Atkins foundation The US beef industry appears to have commissio even documented their expected results . There is a link to the document here , (don't look at the whole blog post if an alternate view will give you apoplexy . The purpose is merely to give a link to the beef industry document
http://carbsanity.blogspot.fr/2014/11/that-new-volek-phinney-study-part-ii_26.html
.If you use funding as an argument rather than looking the quality of the scientific evidence you have to be consistent.