When 42-year-old Cathleen Gardiner's twins were born 17 years ago, doctors told her they were a pair in a million". One had Down's syndrome, while the other did not. Here, Cathleen [tells] their touching and inspiring story: Since Sean was born 17 years ago, I have always taken the view that he is just as wonderful and special as my other two children. While he may have a disability, none of us have ever viewed him as a burden, and ... I refuse to see him as anything but a blessing. The doctors explained that as they were fraternal twins, meaning they came from two eggs ... Lisa was not affected by the condition. Lisa walked at 11 months, while Sean didn't take his first steps till he was three. By two, Lisa was quite the conversationalist, but Sean wasn't able to form sentences until he was nearly four. For the first five years of his life, Sean needed a great deal of care. There was no question of me going back to my job as a technical adviser in a computing company. Looking after him was a fulltime job. Yet despite the considerable difference between the twins, we never treated them differently. We gave them the same toys and spoke to them the same way. Our attitude was that by encouraging Sean to keep up with Lisa, even though he would never manage it, we would be helping him to fulfil his potential. We sent them to the same primary school after doctors advised us that Sean could go to a mainstream school, but we had to explain to Lisa that he wouldn't learn as quickly as she would. She told us ... that she'd help him with his school work. Having a non-disabled twin has really helped Sean to develop - the love they share has given him a unique support in a tough world, and I'm not sure he would have done nearly as well if he didn't have Lisa fighting his corner every step of the way.

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