From the article:
A strong correlation was found between sex hormones and body fat, which was predominantly due to shared genes. Specifically, testosterone and SHBG both showed a 23% genetic correlation with body fat, and SHBG [sex hormone-binding globulin] showed a 29% link with whole body fat. There was no link in terms of environmental factors between sex hormones and body composition.
When measured individually, testosterone had the highest heritability estimate of the sex hormones at 0.65 (heritability estimates are measured on a scale between 0 and 1, with 1 equalling 100% genetic influence). SHBG, weight and body fat also had high heritability estimates of 0.73, 0.83 and 0.65, respectively. Such high heritability values are similar to those previously published, and indicate that circulating testosterone levels are approximately 60% influenced by genes.
Previous studies have shown a well-established relationship between testosterone and body fat composition. For example, men with low testosterone levels are characterised by a high body fat percentage.