A twin study of human obesity

Area of Science:

• Human genetics
• Obesity research
• Twin studies

Background:

• Body mass index (BMI), height, and weight are key indicators of human body composition.
• Understanding the genetic and environmental influences on these traits is crucial for public health.
• Previous research suggests a genetic component to obesity, but the extent of heritability requires further investigation.

Purpose of the Study:

• To estimate the heritability of height, weight, and BMI in a large twin cohort.
• To assess the stability of these heritability estimates over time.
• To investigate the genetic and environmental contributions to the covariation of height, weight, and BMI.

Main Methods:

• Utilized classic twin study methodology with monozygotic (identical) and dizygotic (fraternal) male twin pairs.
• Assessed height, weight, and BMI in a sample of 1974 monozygotic and 2097 dizygotic twin pairs.
• Employed path analysis to examine genetic and environmental influences on trait covariation across time.

Main Results:

• Heritability estimates for height, weight, and BMI were high at age 20 (ranging from .77 to .80) and at a 25-year follow-up (ranging from .80 to .84).
• Concordance rates for overweight were twice as high in monozygotic twins compared to dizygotic twins.
• Path analysis indicated that genetic factors largely accounted for the correlation between height, weight, and BMI over time.

Conclusions:

• Human fatness, as measured by height, weight, and BMI, is under substantial genetic control.
• These findings align with previous twin studies, reinforcing the significant role of genetics in body composition.
• The high heritability and genetic covariation suggest that genetic predispositions play a major role in maintaining these anthropometric traits throughout adulthood.