Whose child are you?

BROTHER AND SISTER by Joanna Trollope (Bloomsbury, £16.99)

When she was 12, my birth sister, whom I met when I was 28 , found our mother's diary in her wardrobe. It made an oblique reference to my own birth and adoption. So when I contacted my birth mother, things also fell into place for the sister I never grew up with. Joanna Trollope's new novel charts the journey of a brother and sister, Nathalie and David, born to different mothers, to understand the why, the how and the who of their adoptions. They soon realise that ahead of them is not a mystical discovery, but an emotional spaghetti junction.

The biggest journey they have to make is not to their birth mothers, but within their current families, and with their adoptive parents. Reactions are explosive. True to life, by the end of the book, most relat ionships are restored. Current relationships mean more than the craved lost ones. Or do they?

Their decision to search and find is lovingly crafted. What starts as Nathalie and David struggling to come to terms with their feelings of abandonment turns into them managing the feelings of their nearest and dearest as they worry about being abandoned by them. Potential abandonment is the currency of these relationships.

Nathalie's husband has an affair. Doubt about each other destabilises the balance between David and his adoptive parents. As with any change in families, it is impossible to evaluate clearly what has been won and what has been lost. Something has been sorted. Something else has fallen apart. If anything, individuals become more autonomous, and more alone.

Nigh on a million people in the UK have been adopted since the 1920s. Early studies found children did well, although the vast majority were adopted as babies, loaded with relative advantages.

Since the Sixties it has been more complicated. The number of babies adopted has tumbled. As older children and those with special needs are placed, so the number of adoptions that break down has rocketed.

The jury is out on the future of adoption. Ideally, you would stay in your own family. Yet parents continue to abuse their children, making it impossible for some children to stay at home safely.

Few adults, looking back, would have wanted to be left at home to be repeatedly hurt. Yet for adults like David and Nathalie, adopted in an earlier generation, when illegitimacy was morally fatal, meeting up with their birth mothers supplies the information they crave about where they came from, but does little to resolve why they were given up.

Trollope has successfully ventured into the inner worlds of the characters and sounded their aspirations and anxieties. They are instantly recognisable to the general reader as well as to the initiated. Importantly, she sees adoption and its ambiguities as an example of contemporary relationship confusion. Many adults are unsure of their fathers, and their mothers' lives defy stereotyping.

As we speak, in London, thousands of unaccompanied refugee children are busy attaching themselves to extended family members, to strangers and to foster carers. They have no choice. Vulnerable children and sympathetic adults collide randomly like highly charged magnets - human or dehumanised encounters with crazy pasts and risky futures. Trollope's novel, with a more stable characterisation, shows that, in the end, feelings triumph over facts.

Unlike David and Nathalie, I am in touch with my birth sister but not my adoptive sister. No two adoptions, no two brothers and sisters, are the same. As an adoptee, I have been stably married for 28 years. My birth sister has been married twice and her third relationship is troubled.