Three separate Brigham Young University studies appear in a special issue of the journal Economics and Human Biology that focuses on obesity and the family.
The sibling scale
According to an analysis of siblings, genetics can only take part of the blame when it comes to childhood obesity.
Economics professor Joe Price and his student Jeff Swigert looked at Body Mass Index and found a lot of variation occurring within the same families:
Identical twins usually differ by 12 percentiles on BMI
Siblings who arent twins differ by 29 percentiles on average
Random pairs of non-siblings differ by 37 percentiles on average
We tend to think of fat families and skinny families, but actually within families, theres a lot of variation, Price said. What it means is that there are things families can do things that families are doing that can cause siblings to turn out differently.
Previously Price has published research showing how parents unintentionally spend more time with certain children based on birth order.
Growing old together
Marriage produces a host of health benefits across the life span, but BYU professor Sven Wilson found one big exception while studying the health of people who get married later in life.
One explanation of the patterns he observed among people age 51 to 70 is that the pressure of the dating market seems to keep Body Mass Index down.
For men, especially, marriage is simply not a weight-reducing institution, Wilson said. The fat and happy moniker seems far more appropriate.
Previously Wilson has shown that spouses often mirror each others health, and that held true in this new study: When one spouses BMI moved up or down, the other tended to follow in the same direction.
Why happiness falls when teen obesity rises
In a third study, BYU sociology professor Renata Forste and her student Erin Moore set out to find exactly what it is about teen obesity that takes a hit on their satisfaction in life.
After self-image, the second-most influential factor for teens is their perception of school. Compared to other teens, those who are overweight or obese liked school less and felt like they were performing poorly with their schoolwork.
Relationships with peers and parents also suffer, and it all adds up to a less happy adolescence particular for teen girls.
Both obese boys and girls experience negative perceptions and evaluations, but girls are more likely to associate these perceptions with reduced life satisfaction or overall well-being than are boys, the authors write.
Explore further: Teen weight began to rise in 1990s, new study finds