The odds were 16 billion to one: Capri and Kenzie Michels, the twins their mother had always considered fraternal, were identical. Rebecca Michels, 37, from Sydney, told Newsweek the DNA result put the probability at 99.999999994 percent.
The twins were born on May 28, 2025, about 30 seconds apart. Nurses suggested a DNA test four days later because the girls looked very similar, and the result came in July 2025, three days after the test.
An analysis that pointed in the other direction
Michels and her husband had reason to believe the girls were fraternal. According to Newsweek, an ultrasound showed the babies in separate bags with separate placentas, leading everyone to assume they weren’t identical.
Sonographers often described the couple as “simply brothers and sisters sharing a house.” Michels, who also has a 10-year-old son named Braxton, said the couple had no reason to question that during the pregnancy.
Newsweek noted that separate sacs and placentas don’t necessarily rule out identical twins, since some identical pairs develop that way.
Why separated placentas don’t prove much
According to the Washington State Twin Registry, identical twins are formed when an egg is fertilized by a sperm and the embryo divides within the first two weeks after conception. The registry says these twins share 100 percent of their genetic material and are always the same sex. Fraternal twins arise from two eggs, each fertilized by a different sperm, and share about half their genetic material, like any pair of siblings.
The placental count is a poor test. Twins Research Australia says about a third of identical twins have separate placentas, as do fraternal twins, so a pair with two placentas may still be identical. For same-sex twins, the organization says, only a DNA zygosity test can confirm whether they are identical or fraternal.
A paper on zygosity knowledge hosted by the University of Melbourne reports the same figure of one third for identical pairs with separate placentas. He adds that nearly one in six parents in his study reported being misinformed about the zygosity of their twins during pregnancy.
The swab, the wait and the result
Michels told Newsweek that seeing how similar the girls looked made the couple curious, which is why they followed the nurses’ suggestion. The test was carried out in July 2025 and the response came three days later. Newsweek did not name the testing company.
The result gives a probability of 99.999999994 percent that Capri and Kenzie are identical, and indicates that they are 16 billion times more likely to be identical than fraternal. Michels described the result as “a nice end to all the surprises.”
Read a result of 16 billion for one
Such a figure is a probability and not a measure of how similar the girls are. An Australian supplier, Identilab, explains on its site that the DNA profiles of identical twins will be the same and those of fraternal twins will be different. It says its report lists every DNA marker for each twin, along with a probability statement, and gives an example of twins about 20 billion times more likely to be identical than fraternal, or 99.99999995 percent. This vendor is not named in the Newsweek report, and the example is only an illustration of how these results are written.
The paper hosted by the University of Melbourne describes the gold standard as a test of 12 to 15 markers, with a pair considered identical when all markers match.
Why parents test their twins
Twins Research Australia says knowing zygosity can be important for health and family life. It lists the relationships between twins, assesses the risk of disease, tissue compatibility for organ transplants, legal and educational issues and the possibility of the mother or close relatives having more twins. In one of his studies, about a third of the twin participants and a third of the parents were unsure or wrong about the twins’ zygosity before DNA testing.
The paper published by the University of Melbourne adds that accurate zygosity is important for perinatal health, personal identity and peace of mind, and that most participants who learned their true zygosity reported positive emotions.
Twins are not uncommon. The National Center for Health Statistics reported in its Health E-Stat 117 that the twin birth rate in the United States increased from 33.9 to 30.1 per 1,000 births between 2014 and 2024.
For the Michels family, the answer settled a question that had remained open since the girls’ early days. Capri and Kenzie are identical and their mother says the news matches the surprises that preceded it.
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This article was produced with the help of AI and edited for accuracy from the sources linked above.
Image: Photo by and ©2006 Dustin M. Ramsey (Kralizec!) – CC BY-SA 2.5/Wikimedia Commons. Stock photo, not the Michels family.
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