Paternity tests are famous for producing shocking results, but even Maury Povich couldn’t script what has happened to a 34-year-old Washington man who was given shocking news pertaining to his infant son and his DNA sequence.
After producing a son through fertility treatments, blood work showed that the child’s blood type did not match his father or his mother. Alarmed (naturally), paternity tests were performed, confirming the initial results. Upset (naturally), the couple feared there was a mix-up at the clinic and called to inquire about the potential mistake. The clinic checked their records and stated no mistake was made.
How could that be? To almost anyone, this would be a bizarre, daunting affair that generates more questions than it answers. With that in mind, the couple contacted Barry Starr, a Stanford University geneticist who runs Ask A Geneticist, a website that allows everyday people to ask puzzling questions about genetics and have them professionally answered. Starr told the couple to take a more comprehensive genetic test, which produced some earth-shattering results.
The 34-year-old man from Washington was definitely related to his infant son — both as a father and as an uncle.
Following what can only be assumed to be a recreation of the exploding head scene from Scanners, the man learned that his sperm actually belonged to a twin he had absorbed in the womb, making this 34-year-old man from Washington a genetic “chimera.” The absorption process normally takes place early in pregnancy and since there are few instances when outward signs of absorption are evident, when the two egg cells become one no one is the wiser. There are, however, some chimerics who have outward physical characteristics linked to their chimerism. A chimeric could have two eyes that are different colors, for example, or their skin may be striped or swirled where the two lines of DNA meet.
The 34-year-old man from Washington’s skin was striped.
About 1 in 8 single childbirths are thought to have initially been multiple pregnancies. Cells from the miscarried sibling can either be absorbed into the body of the mother or can be absorbed by the surviving twin. What makes this man’s case even more unusual, however, is that some of the cells he absorbed were germline cells, which develop into eggs or sperm. When his fraternal twin died, the embryo that would become the 34-year-old man from Washington absorbed his twin’s mobile and migratory germline cells, which were then folded into his DNA sequence. These cells were not rejected because the surviving twin lacked immune development capable of seeing the germline cells as foreign. If the surviving twin’s immune system was capable of making that distinction, the DNA sequence overload would have been fatal.
A 34-year-old man from Washington now knows that his son is his own cousin and he is the boy’s father and uncle. That’s going to twist the branches of the family tree a bit, I’d say. But his story is absolutely fascinating and could help shed some light on a genetic anomaly that may be common than we think, but is difficult to identify.
What would you think if you were to find out your DNA sequence is not just yours, but also contains the ghost of your miscarried twin?
Featured image by Calliditas and is in the public domain.
