Epidemiological data from NHANES is inaccurate and incomplete. It's impossible to reach an accurate conclusion even at the level stated. To state the suspected reasons is to extend pure, unfounded speculation:
- Chemicals that might be "weight inducing"
- Prescription drugs
- Changes in microbiome
- Eating more meat (not borne out by other studies)

Interesting that the changes in types of "food" available weren't part of the reasons cited. The underlying assumption and rationale is based on the CICO model, where one would have to exercise more and eat less today to reach the average weight of people's parents at the same age, is complete folly.

What is not taken into account are the major differences in foods consumed today compared to the foods our parents ate. In addition, when my parents prepared food, they did so at home without fast and/or processed food. I never would have been allowed a soda at the dinner table and rarely any other time.

Genetics has no direct influence on these assumed dynamics, but epigenetics forming the environment in which we live and consume including food types does have a great influence. Recent discoveries show that environmental influences impacting one generation are inherited by subsequent generations at the cellular level, not the genetic level. So, poor health can be passed on to multiple generations. It's just not due to a mutation at the genetic level (that takes too long); rather, it's due to characteristic influencing genetic manifestation at the cellular level. Environmental influences turn genetic characteristics on or off.

The empowering dynamic about this understanding of how food (environment) plays such a large role in health outcomes means that we can reverse the damage. Successful reversal also benefits future generations in the same manner.