I think there is a strong genetic link. I know that I am very similar to my older son. He was born at 36 weeks but did not need to spend any time in the NICU. My younger son was full term and he is more mildly affected by SPD.
Here's another post I made on a Facebook SPD support group in response to adults with SPD:
"I had never heard of SPD until 2008 when my older son was diagnosed (1st grade). He received OT for 2 years with much success. He has also benefitted from continuing social skills groups at school and at a private psychologists' office. He's now in 4th grade [5th grade now] doing do much better, though he still struggles with anxiety and low self-esteem.
It's just been in the last 9 months [over a year now] or so that I've been seeing many of sensory issues in myself. I was always a very shy child, quiet, rarely spoke up, afraid to draw any attention to myself (good or bad). I followed the rules and tried to please my parents and teachers.
I realized recently that as a preteen/teenager I was doing my own OT. I loved changing my bedroom furniture around. I would do it all by myself, moving my bed, clothes dresser, and a 6 foot tall shelf that held my books and games. Doing gross motor activities. I always thought I just had an eye for interior designing, but I was satisfying an inner need of my brain and body. I would change my room at least 1-2 times a month. Luckily my mom never minded.
As I said in my other post, I hate talking on the phone. I put off making phone calls all the time. I have a mini-panic attack thinking about having to talk on the phone. Unless it's an immediate family member or a very close friend, I have to plan out (and often write down) exactly what I'm going to say. I have 2 phone calls now that I've been putting off for weeks.
It was a big hinderance in my jobs in the '90s, before email and Internet. Thank goodness for email and Internet!
I have always preferred to be barefoot, going without shoes at least. My mom always tells me about when I was a baby and toddler that I would take off my shoes and socks and pull the laces out of the shoes (before Velcro) and she'd have to search the house for them all. I refused to eat meat as a teenager, hating the texture of red meat. I lived on cereal, yogurt, pineapple, and broccoli. I ate only to stay alive, it wasn't an enjoyable activity. There are a few sounds that make my skin crawl. If I can't make them stop, I have to plug my ears and hum so I don't hear them. One of them is the sound of my dog licking himself. It's like nails on a chalkboard to me. Everyone seems to watch TV louder than I like it.
I've seen psychologists and therapists on and off for the last 15 years. I've been diagnosed with depression and anxiety, and one doctor said I had OCD thoughts. But in another forum [this one--SPD Support], I found that my "little movies" as I call them (short visions of awful things happening to myself and those I love, most often "seeing" my car lose control and drive off the edge of a bridge as I cross it) are probably SPD related rather than OCD. I thought I was the only one who had those and some SPDers spoke up that they'd had them as well!
I get very irritated and snap at people when there're too many people or commotion going on around me. I need alone time every now and then to recharge my battery.
I see some sensory issues in both my parents, though maybe a few more in my mom. I'm not sure if it's been proved yet, but it seems to have a genetic connection."
It seems like it's on a spectrum, much like autism. Some people are very low on the scale and can handle most sensory issues that come up in daily life. They may be mildly annoyed by certain noises, lights, fabrics, etc., but they are able to live a normal life. Some people are very high on the scale and are severely disabled by the sensory issues they have.
