Heteropaternal Superfecundation in Dizygotic Twins: Biological Mechanism, Genetic Identification and Forensic Implications
Author : Dr. Kaufiya D Sayyad, Pruthviraj S. Motherao, Vaishnavi V. Shete, Divya S. Jadhav, Dhiraj L. Chandile and Astha B. Lomate
Abstract :
Heteropaternal superfecundation (HS) is a form of dizygotic twinning in which two oocytes released during the same ovulatory cycle are fertilized by sperm from different biological fathers. Although the phenomenon is uncommon and is most often recognized during disputed paternity investigations, published reports suggest that its true frequency is difficult to determine because many cases are never investigated or reported. This review summarizes the biological basis of HS, the genetic relationship between heteropaternal twins, approaches used for forensic identification, reported frequency estimates, and the implications for paternity testing and twin research. Early investigations relied on blood-group, HLA and protein markers, whereas modern forensic investigations use autosomal short tandem repeats (STRs), Y-chromosome STRs and amelogenin analysis. A 1992 database study identified three HS cases among 39,000 parentage records and reported a frequency of approximately 2.4% among dizygotic twin cases involved in paternity disputes, while emphasizing that this estimate should not be generalized to the population. A 2020 Colombian case demonstrated exclusion of the alleged father for one twin while supporting paternity for the other. A 2021 report further demonstrated the use of microhap sequencing of maternal plasma cell-free DNA with conventional STR confirmation. A 2025 case report and literature review examined 2,679 paternity tests over ten years and identified one HS case among 31 twin-related exclusions. Overall, HS illustrates why both dizygotic twins should be tested individually in paternity disputes and why continued development of sensitive molecular methods may increase recognition of previously undetected cases.
Keywords :
Heteropaternal superfecundation, dizygotic twins, superfecundation, paternity testing, STR, Y-STR, forensic genetics, microhaplotype.
