As Disraeli allegedly put it,
"There are three kinds of lies: lies, damned lies, and statistics".
Some years ago, a British woman was convicted on the basis of expert evidence that there was almost no chance of having 2 cot deaths in the same family. It was obvious to almost everyone but the judge and jury that it was a miscarriage of justice, as although cot deaths are quite rare, a physiological cause may run in the same family, increasing the chance of multiple deaths. (By British law, the fact that a court got the facts wrong is not enough reason to overturn a verdict, as the court is "the sole judge of the facts". She was eventually released when lawyers found an unrelated technicality. The expert witness was struck off by the BMA but later reinstated when a judge ruled that expert witnesses should not be afraid of giving evidence.)
AS Dena said, a genetic or physiological cause could also increase the likelihood of having multiple trans children in the same family. You can't take a mean from the the general population and assume that it applies to any small sample that you choose.