5

The Thin Privilege FAQ explains:

Weight is about 50% - 80% heritable (sources disagree, but here’s a study that shows it to be 77% heritable). Height, for comparison, isn’t 100% heritable (I’ve seen it pegged in the 70% - 80% range but I still need to dig up this source).

It seems dubious to me that height and weight have similar heritability (unless I'm misunderstanding what heritability means).

  • 2
    Speculation: Height is only affected by your childhood diet and environment, whereas weight can be affected by your adult-age diet and environment. – Andrew Grimm Jan 21 '15 at 23:15
  • Without you mentioning what you think heritablity means it's hard to say whether you are wrong. It's however quite plausible that you are wrong as the term isn't straightforward. – Christian Feb 4 '15 at 12:31
  • @Christian I presumed that heritability was the percentage of some feature of a person that their genes contributed to. E.g. something like hair colour would be very heritable, and something like music taste would not be at all (near to 0%). – rlms Feb 5 '15 at 17:39
  • 1
    @sweeneyrod : Heritability isn't about a single person. It's about a population. It's how much of the difference of a trait in a population is due to genes. – Christian Feb 6 '15 at 18:17
5

It looks like for young people (20's) both height and adiposity hover around .80. But as people get older genetic factors become less important for adiposity but remain somewhat stable (around .80) for height.

A Twin Study of Human Obesity
http://jama.jamanetwork.com/article.aspx?articleid=359582

Height, weight, and body mass index (BMI) were assessed in a sample of 1974 monozygotic and 2097 dizygotic male twin pairs. Concordance rates for different degrees of overweight were twice as high for monozygotic twins as for dizygotic twins. Classic twin methods estimated a high heritability for height, weight, and BMI, both at age 20 years (.80,.78, and.77, respectively) and at a 25-year follow-up (.80,.81, and.84, respectively). Height, weight, and BMI were highly correlated across time, and a path analysis suggested that the major part of that covariation was genetic. These results are similar to those of other twin studies of these measures and suggest that human fatness is under substantial genetic control.

A Cross-sectional Examination of Height, Weight, and Body Mass Index in Adult Twins
http://biomedgerontology.oxfordjournals.org/content/50A/4/B237.short

A cross-sectional twin design was used to study the developmental nature of genetic and environmental influences on height, weight, and body mass index. The sample of same-sex adult male and female twins consisted of 586 monozygotic and 447 like-sex dizygotic twin pairs aged 18 to 81 years. Means and variances suggested normative age differences for all three physical variables. Biometrical model-fitting with maximum likelihood methods of parameter estimation indicated that the general best-fitting model across the age groups for height, weight, and body mass index was one in which the genetic effects were additive and the environmental effects were from nonshared, idiosyncratic experiences. The best-fitting cross-sectional biometrical model for height, weight, and body mass index indicated that additive genetic variance remained stable while nonshared environmental variance increased with age. This increase in environmental variance but stable genetic variance resulted in decreasing heritability with age for height (heritability ranging from 0.89 in the youngest group to 0.87 in the oldest), weight (heritability ranging from 0.86 in the youngest group to 0.70 in the oldest), and body mass index (heritability ranging from 0.82 in the youngest group to 0.63 in the oldest).

  • Do you know the actual heights and weights of these studies? Seems like it may be based on normal weighted subjects and reasonable fluctuations, not BMI > 30. – Raystafarian Jan 27 '15 at 18:10
  • @Raystafarian No, unfortunately I don't have access to the full articles. But, as far as I can tell these numbers represent a spectrum from healthy BMIs on into unhealthy BMIs. I never got the impression from the question that it was asking about clinical obesity. To avoid confusion I will change the wording in my answer to adiposity. Hopefully this won't be confounded with a diagnosed illness. – Adam Phelps Jan 29 '15 at 5:18
  • Yeah, the "This is Thin Privilege" site is basically a promotion of unhealthy weight, disguised as something else. – Raystafarian Jan 29 '15 at 10:20

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