Boy / Girl Identical Twins

"Are they identical?" Many parents of twins hear this question from passersby peeking in carriers at two little bundles of blue or two little bundles of pink. When fielding the "identical" question, parents with one bundle each of blue and pink often feel the well-intentioned stranger is a little daft.

However, an extraordinarily rare subset of multiples' parents actually can say, "My pink and blue are, indeed, identical."

First, let's take a look at some basic high school biology. Monozygotic (MZ), or identical, twins are the result of one fertilized egg splitting into two zygotes very early in the pregnancy. MZ twins each have almost indistinguishable sets of chromosomes. Dizygotic (DZ), or fraternal, twins are the result of two different fertilized eggs. DZ twins chromosomally are as singleton siblings, save for the fact that they share a birthday. Fraternal twins can be boy/boy, girl/girl, or boy/girl. Most of the time, identical twins are either boy/boy or girl/girl. Generally female children have two X chromosomes and male children have one X and one Y chromosome.

However, Turner's Syndrome (also known as gonadal dysgenesis), occurring in approximately 1 out of 2500 births, is a condition where a fetus begins male, but then loses the Y chromosome, resulting in a female child with XO sex chromosomes.

Apparent symptoms of Turner's Syndrome may include: extremely short stature, delayed or nonexistent puberty, a webbed neck, a low hairline at the back of the neck, drooping eyelids, lower-set ears, abnormal bone development, excessive moles, swelling of the hands and feet, infertility or sterility, kidney dysfunction, obesity, hypothyroidism, high blood pressure, hearing problems, diabetes, and heart trouble.

As Turner's Syndrome is a chromosomal disorder, there is no cure. However, treatments do exist. Growth hormone can be given, giving the child more height. In vitro fertilization may assist a woman with Turner's Syndrome in becoming pregnant. Hormone therapy (estrogen) can help with bringing the onset of puberty.

As you might imagine, girls with Turner's Syndrome may suffer from poor self-image, low self-esteem, and depression. Therapy and support groups may help relive these symptoms.

Parents of boy/girl identical twins will have it rough as well. They may have to repeatedly go through the litany of the high school biology lesson, explaining the chromosomal differences between males and females, and then walking through the cactus garden of how all this information pertains to their twins. Not to mention, the repeated trips to different doctor's offices, experiencing with their child procedures, tests, and prescription after prescription.

So, you see, having boy/girl identical twins is not impossible, just improbable. With this probability comes a host of other medical, emotional, and physical issues to contend with. However, like other parents of twins, parents of Turner's Syndrome would not trade the messy miracle of multiples for anything.

(Edit:Ruby)