It is possible that the reason the lizards were conjoined was partly due to the low amount of genetic variation that stemmed from having parents that were siblings, according to the report. In 2002, research was published on snakes, called Natrix tessellata, which showed a link between an increased rate of developmental abnormalities and a low genetic variability in small populations that had a limited number of ancestors.

Moreover, a study on sand lizards "revealed a significant effect of parental genetic similarity on the risk of hatching malformations," van Schingen said.

However, previous reports have also pointed to other potential causes of malformations in reptiles. For instance, in 2010, researchers described a case of a crocodile hatchling with eight legs and two tails in Venezuela that was found in an area that was exposed to chemicals from agriculture, according to the report.Another cause of deformations in reptiles may be adiet that is not well-suited to the needs of animals kept in captivity, which has previously been the case with bone malformations in green iguanas, van Schingen said.