I’ve always said that they’re either identicals with a few physical differences, or fraternals that look an awful lot alike. I’ll explain, perhaps, in a later post how it is that after more than three years we still weren’t sure, but for now, the results:

Dear Mr. Spencer:

Our laboratory has successfully completed your zygosity test and your test results have been mailed. Thank you for your interest in our zygosity testing services. As requested when you placed your order, we have included a copy of your test results in this email.

We are pleased to report to you the results of the twin zygosity test that you requested. Analysis of the DNA indicates that J S and S S are monozygotic, or more commonly referred to as identical twins.

We first isolated DNA from cheek cells from the swab kits that were returned to our lab. We amplified the DNA using a technique called PCR. Next, we analyzed 7-8 standard DNA markers (D5S818, D13S317, D7S820, D16S539, vWA, TH01, TPOX, and CSF1PO) and determined that the highly variable DNA markers were the same for both twins. Thus, there is greater than a 99% probability that the twins are monozygotic.