When I was pregnant with my first child, my obstetrician-gynaecologist referred me to a genetic counsellor "just in case". I have a condition called X-linked hypophosphatemia (XLH), which can lead to a form of dwarfism. I was a spontaneous case; there had been no earlier family history. No road map.
The counsellor did not seem too worried. "Don't sweat it," he said. "Frankly, this is so rare, you'd have to marry a guy from the rickets clinic to pass it on." I gave birth to my daughter Annabelle seven months later. She did not have XLH.
Six years later, I stood in a neonatal intensive care unit looking at my son, Walker. Because my husband and I had a rare blood incompatibility, Walker needed multiple transfusions. But what I was staring at as he lay in his incubator were his legs - I recognised something in them, a kind of curvature that felt as familiar to me as my own face.
"He has XLH," I said to his doctor. She said: "I wouldn't worry about that - we have enough here to worry about." But a day later she came and told me: "You were right. His phosphorus is very low. We're pretty sure he has what you have."
Because of a mutation on the PHEX gene, people with XLH do not absorb phosphorus, resulting in short stature, bowed legs, soft bones and weak teeth.
When I saw the genetic counsellor before Annabelle was born, the genetics of my condition had not yet been mapped and, in fact, the counsellor was wrong. I have a 50 per cent chance of passing on XLH. And since Walker was born, I've had another daughter, Eliza, who has XLH as well.
Several years ago, a relative, who is quite religious in a way I am not, called me unexpectedly. She wanted to apologise as she had always thought I should never have children; "God would not want you to have children" was how she put it.
Yet now that I have three of them - three "beautiful children", she said - she wanted to let me know she had been wrong. It was a bit of an awkward moment, like when someone says you look fabulous in a way that lets you know how terrible they thought you looked before.
When I found out Walker had XLH, I mourned briefly - mostly for the image I'd had of a tall, gangly teenager, the kind I had never been. But I never once regretted him or his XLH, and I certainly never imagined other people thinking about it or judging me for having had a child with a disability.
Her words irked me but, eventually, I came to understand that it is probably difficult for an abled person - a person who considers herself "normal" - to imagine taking the risk of passing on what is considered by most to be a fairly significant disability.
XLH patients, the Merck Manual Of Diagnosis And Therapy tells us, are often quite robust, apart from their short stature and odd side-to-side gait, and also the pain they suffer - muscle aches, bone aches - and being "quick to fatigue if asked to walk any distance".
My two younger kids and I all hover around 1.5m. This is not such a big deal for me; it is more so for my son, and all of us struggle to stand or walk for any length of time.
Occasionally, I come across the term "designer baby", and I am reminded that some parents now have the option to screen or modify the genes of their unborn children to ensure or avoid certain traits. It always gives me a feeling of unease.
Obviously, I did not take this route - partly because, at least with my son, I never had to actually make the decision. My third child was a late midlife accident. I chose to have Eliza despite the possibility she would have XLH, but would I have made the same decision in a planned pregnancy or if given a choice much earlier in the process?
I can't help suspecting that - because of advances in genetic mapping, genetic testing, the sheer range of prenatal choices - chances are, in a generation or two, there will be no one in the world who has XLH, no one who looks like me or my children - at least not in the developed world - and I don't know how to feel about that.
I am aware that some studies do show that short people score fewer points on "happiness scales", whatever that might mean, but we are not the average study subjects. We are ourselves, individuals; we are what we are - short and proud of it. We are people with a disability.
Sometimes people stop us and ask us what is wrong with us; most of the time I can see that people notice, but they don't say anything. Walker is more visibly disabled, which makes Eliza feel bad. She says sometimes she feels like a fraud because she has the same thing but, in her case, "you almost can't tell".
Walker rides a bicycle. Eliza does yoga. Both of them pursue these physical activities with fierce and single-minded passion. Both do so because there are other physical activities - walking, running - that they cannot pursue without difficulty. (Oddly, my least athletic child is my oldest, Annabelle, who regularly proclaims she hates all sports.)
Pain - both physical and psychic - is a part of my two younger kids' daily experience, and it is the part that is the hardest for me to get over. Perhaps this is what my relative meant. Perhaps sparing your loved one that psychic pain is the reason some people give their short-statured but otherwise perfectly healthy children human growth hormone, so they might grow just a tad taller.
Most of the time I believe my children will transcend the parts of their disability that could make them suffer.
Walker might be only 1.52m tall, but he is in every conceivable way an engaging personality. He has friends, wild schemes for the future, a wicked, deadpan sense of humour. Eliza is all darting motion - ups and downs. She sings in the shower; does cartwheels on the lawn. She also struggles with an eating disorder and anxiety. And Walker, normally even-keeled, occasionally gives in to fits of rage and frustration when, tired of the effort of simply moving through a day, or being left out at school, he punches walls, rides his bicycle too fast.
How much of this can I really blame XLH for? My oldest would not say she has a perfect life. At 23, Annabelle is floundering a little, unsure what to do with her life. She adopts stray dogs. She gets tattoos. She works in a supermarket bakery and is struggling to finish college. She writes killer poems that are also very angsty.
Sure, XLH has a cost, but so does life.
I know what "designer baby" people would say: the more "advantages" - beauty, height, intelligence - the better the life chances, the better the life. But I am not sure I believe them.
Life is more than that.
• The writer is the author of three books of poetry, most recently, Wen Kroy, an editor of Beauty Is A Verb: The New Poetry Of Disability, and director of Gemini Ink, a literary arts centre in San Antonio.