Heritability of quantitative orbital traits.

We conducted a study of 63 couples and their 242 normal children from northeastern Brazil (no facial malformations or deformities) to evaluate the heritability of 4 quantitative traits of the orbital region adjusted by covariance for sex, age, (age)2, sex x age, and sex x (age)2. The heritability is estimated as 0.514 for the mean horizontal diameter of the palpebral fissures, 0.454 for the interpupillary distance, 0.390 for the internal intercanthal distance, and 0.337 for the external intercanthal distance. The heritability of the first principal component of the orbital region is estimated as 0.418.