The sibling factor

Euan has a younger brother, Adam, who is nearing his third birthday - roughly the age that Euan's difficulties started to become apparent. So far there has been nothing remarkable about Adam's development: he talks like any other two-and-a-half-year-old, probing the mechanics of language as if it's a shiny new gadget and beaming with glee when he produces a fluent sentence. He looks people in the eye when they talk to him and displays no obsessiveness in his play or his behaviour. Yet autism is an issue for Adam too, and will increasingly be so as he and Euan grow up together.

The gap in the brothers' ages - two years and four months - is commonly seen as ideal. Certainly at the moment they get along famously, whether rolling around on the living-room floor, singing songs together or scrambling over the climbing frame. At the moment Adam is utterly unaware that Euan is different from other children; in fact, Euan's restricted communication mean that in many ways they operate on the same level. Some time after Christmas we noticed Adam was pulling ahead in his language and using more natural forms of speech: whereas Euan repeats things he has been told mechanically, Adam is able to adapt what he hears and employ it to form his own sentences. Imagine giving two children the same Lego set: one of them constructs and dismantles the design on the box again and again, while the other shakes the bricks onto the floor and uses them to create his own things. That's more or less the difference in Euan and Adam's language.

Because he is unaware of Euan's condition, Adam sometimes copies his older brother's autistic habits. When Euan goes downstairs in the morning and wants to play in the living room, he bangs on the door until one of us comes down and opens it; the other morning Adam did the same thing, believing, perhaps, that because we don't tell Euan off about it, it must be the right way to ask. Yet the bigger worry is what happens when Adam does start to notice that Euan is different from other children. Will he shun his brother in the school playground, or protect him? When he reaches his teenage years, will he resent his brother for being different, or feel constricted by the association? Will we, as parents, lean on him too much to look out for Euan - who is, after all, the older brother?

And which will be the greater danger: neglecting Adam in the struggle to attend to Euan's needs, or overloading him with expectation as the "normal" child? At the supermarket this weekend Adam delighted in his new-found ability to "surf" on the side of the trolley as I pushed it along. "I'm finally finding out how a two-year-old is supposed to behave," said Magteld with a wry smile, reminding me that "normal" children provide plenty of challenges too.