Early Intervention is Critical
Hi, everyone~... I'm the mom of a 28 year old with a mild case of SPD (4 on a scale of 1-10). It could well be genetic, as I recognize 4 out of 15 SPD symptoms in myself and I'm 60.
My son had sleep issues, (I felt like I never slept for about 5 years) transition-to-waking issues, sensitivities to clothing, textures (wind on his face at the swing, sandboxes, wearing shoes, etc.) food texture sensitivity, severe motion sickness, passing out at the dentist,etc. etc. etc. so I've been through it all as well. No one understood.
My advice is to sign your child up for as many different therapies and activities as your child can handle and you can afford, at as early an age as possible. A neurological Dr's diagnosis will facilitate partial insurance coverage for speech, occupational and physical therapy. We also paid for a music therapy class and did as many low-cost, family activities as well: puddle-jumping, nearby parks, the zoo, children's museums, organized sports, etc. All of this helps stimulate new neurological pathways and in time can help your child cope and adapt to our world. But if you didn't start early to help your child, start now. Later interventions are better than no interventions at all.
Finally, no one understood my "quirky"son, either. And they thought I was overdramatizing the situation. These days, with the internet, I would just send well-meaning friends and relatives links from well-respected, medical sites so you can educate them without arguing about it. Once they see the symptoms listed and remember you complaining about those very same symptoms, they'll finally understand.
Good luck to you all. My son graduated from college, has a fiance, and I'm currently educating him on his childhood symptoms so he can watch out for them with HIS children.