Man fails paternity test because of unborn twin’s DNA

Posted at 1:14 PM, Oct 25, 2015
and last updated 2015-10-25 13:14:09-04

A 34-year-old Washington man’s unborn twin caused confusion for a couple seeking the results of a paternity test.

The parents, who wish to remain unnamed, went to a fertility clinic and welcomed a healthy baby boy in June 2014. But problems began when they realized their son didn’t have the same blood type as either parent.

They took an at-home paternity test, which revealed the man wasn’t the child’s father, BuzzFeed reported.

“You can imagine the parents were pretty upset,” Barry Starr, a geneticist at Stanford University, told BuzzFeed. “They thought the clinic had used the wrong sperm.”

It turns out the man is a chimera, meaning he absorbed the genes of his twin, who died early in the pregnancy.

According to a case study, the man’s DNA excluded him as the boy’s father, but still showed a relationship.

“To our knowledge, this is the first reported case in which paternity was initially excluded by standard DNA testing methods and later included as the result of the analysis of different tissues. This case of chimerism yielding a false exclusion is thought to be unusual,” the study concluded.