My amazing son who I'll call J, is nearly three, and was diagnosed soon after birth with a relatively rare genetic condition. We don't yet know how it will affect him as he grows older, but so far he has battled an array of medical problems. One thing's for sure, our little family's life will never be 'normal'...
Some of my friends have seemed confused by me using the term, perhaps because to them it conjures up an image of a person who has severe learning difficulties and physical disabilities, which my son does not have.
He's a bright, chatty, active person, and looks 'normal' at first glance.
But then, every time I see my son with other children the same age as him, I see how different he actually is.
At a third birthday party this week, for instance, a typical thing happened. A girl his age brushed past him and knocked him to the floor without even noticing.
This happens to J most days as he mixes with other two and three-year-olds, many of whom seem twice his height and weight.
J, who's about to turn three, has only been walking for six months, and is quite tiny, so he's not anywhere near as confident and robust on his feet as his peers.
A little fall like that leaves him shocked and crying, while most others his age wouldn't topple in the first place, and if they did, would jump up again without a whimper.
Then there was our visit to the adventure playground last week with a boy exactly J's age, who climbed up an enormous twisty slide and hurtled down it.J could only stand holding my hand, watching, amazed - at this stage, he could not so much as climb the steps alone.
His language and dexterity are also slightly delayed - he's not yet having conversations about why things happen, and he can't draw a circle or a straight line. But then, I think a lot of 'normal' children his age, especially boys, are the same.
And in other areas, I think J is advanced for his age - most of all, in his kindness and consideration for others. He is good at sharing and never pushes others or snatches.
At nursery, the others his age (and younger!) are enormously protective of J, treating him like a younger child.
His key worker has even had to explain to them that he is the same age as them. They adore him and rush to pet him and feed him, which I find really touching, but I also worry about what school might be like for J when he's older and other children aren't so sweet.
Especially because he's a boy, and it's probably not easy in this world to be a small, fragile, sensitive boy.
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