Table 1.
Twin studies on heritability of caffeine-related traits
| Study | Number | Sex | Group | Traits measured | Heritability | Notes |
|---|---|---|---|---|---|---|
| Carmelli et al. (1990) | 9,920 | ♂ | US veterans Caucasian | Cups of coffee per day | 0.36 | Adjusted for smoking and alcohol |
| Hettema et al. (1999) | 7,728 | ♂+♀ | Virginia Caucasian | Average daily consumption of coffee and tea. Also measured tobacco and alcohol use | 0.57 (♂) 0.58 (♀) |
0.67 caffeine specific 0.72 caffeine specific |
| Kendler and Prescott (1999) | 1,934 | ♀ | Virginia Caucasian | Caffeine (coffee, tea, soda) use, heavy use (>625 mg), toxicity, tolerance, withdrawal symptoms | 0.40 0.45 0.35 0.43 0.77 |
Tolerance Toxicity Withdrawal Overall use Heavy use |
| Kendler et al. (2007) | 4,865 | ♂+♀ | Virginia Caucasian | Caffeine dependence symptoms (sum of symptoms of tolerance and withdrawal during maximum) during period of maximum caffeine intake | 0.34 | 0.91 caffeine specific |
| Kendler et al. (2008) | 1,796 | ♂ | Virginia Caucasian | Yearly levels of caffeine use from adolescent to adulthood Also measured alcohol, cannabis, nicotine use |
0.30–0.45 | Heritability rises from age 9–14 and then remains stable |
| Laitala et al. (2008) | 10,716 | ♂+♀ | Finland | Daily coffee consumption in 1975 and 1981 | 0.56 0.45 |
In 1975 In 1981 |
| Luciano et al. (2005) | 8,167 | ♂+♀ | Australia | Daily coffee and tea consumption; preference of coffee over tea | 0.51 0.26 0.48 0.42 |
Coffee Tea Total caffeine Preference for coffee over tea |
| Luciano et al. (2007) | 7,616 | ♂+♀ | Australian | Coffee-attributed insomnia | 0.40 | |
| Swan et al. (1997) | 712 | ♂ | US veterans Caucasian | Consumption of coffee (cups per day), cigarettes, alcohol | 0.36 0.28 |
Coffee; 0.72 coffee specific Common factor for joint substance use |
| Swan et al. (1997) | 4,593 | ♂ | US veterans Caucasian | Heavy consumption of coffee (>5 cups/day), cigarettes, alcohol | 0.51 0.41 |
0.59 coffee specific common factor for coffee and smoking |
| Teucher et al. (2007) | 3,262 | ♀ | UK | Food frequency questionnaire (servings of coffee calculated) | 0.41 | |
| Vink et al. (2009) | 4,495 | ♂+♀ | The Netherlands | Coffee consumption and preference over tea | 0.39 0.62 |
Coffee Coffee preference |
Heritability is calculated by partitioning sources of variation into genetic and common factors using twin modeling. Common factor refers to heritability that is shared across substances. Further details are provided in text and can be found in the individual papers