'Who Do You Think You Are?' is a hugely popular TV series that explores the geneology of well-known public figures. RTE also has its own version, an almost exact replica.
The series are both moving and illuminating. Seeing the terrifying and acerbic Jeremy Paxman cry when he realised his great-great grandmother had to live in a workhouse in dire poverty provided new insights into the power that our personal, historical narrative has over us.
Our identity has many components, including our nationality, our culture and religion, our sex and skin colour, to name just a few and arguably, most important of all, who our parents were and the lineage from which we have emerged.
Children who are adopted frequently seek out their birth parents, not out of any disloyalty to their adoptive family, but in the search for who they are.
Questions such as where did my blonde hair come from, what is the source of my interest in sport even though my adoptive parents have none? How is it that I can play musical instruments so well when I have never been formally taught? Where has my fiery temper come from?
Imagine if the people you assumed were Mam or Dad really weren't and that your parents were not those who reared you.
It is so as to avoid the trauma of discovering information such as this and identity confusion that it generates that adoptive parents nowadays bring their children up knowing that they are adopted and that their adoptive Mam and Dad are not the same as the parents who conceived them.
And this honesty works well.
Ronan Farrow (born Satchel O'Sullivan Farrow) is the grandson of the Irish film actress Maureen O'Sullivan and the child of Mia Farrow. The world thought Woody Allen was his father since Ronan was born during Farrow's relationship with him. Less than two weeks ago, his paternity became the subject of speculation when Farrow, asked if he might be Sinatra's son, replied "possibly". No paternity test has been carried out. Ronan tweeted: "Listen, we're all possibly Frank Sinatra's son." Let's hope his nonchalance was a reflection of how he truly felt and not a defensive quip to conceal his deep confusion. Because, if he was unaware of this possibility, he may face personal uncertainty and self-doubt.
Those who become aware, as adults, that their parents are not who they believed them to be, are likely to experience a sense of betrayal. They will rightly ask why it was they grew up in a family that was based on an untruth.
Even if parents concealed the truth about their parentage (and in my experience it is always done with the best of intentions) only recriminations and anger will follow unprepared discovery of the truth.
Apart from the psychological difficulties that concealing this information causes, there are also physical health reasons for disclosing this, such as a family history of cancer or heart disease.
For example, a woman whose biological mother has breast cancer might herself be a risk if she has a genetic predisposition.
Similar considerations apply to those when there is a family history of heart disease or of a number of other medical conditions. Only knowledge of this risk could allow for preventive measures to be instituted.
More rare than the imperative to prevent illness is the necessity to prevent siblings or close relatives from unknowingly forming relationships with each other.
There have been a number of recent reports of siblings marrying each other in these heart-rending circumstances. Genetic sexual attraction (GSA) is the name for sexual attraction between genetically related couples, siblings, parents and children, or cousins, but without either having knowledge of the biological tie.
The term seems to have been coined by a woman Barbara Gonyo who was unprepared for the sexual attraction she felt on being reunited with the 26-year-old son she had given for adoption as a baby.
These tragic stories are rare but could potentially escalate as anonymous sperm and egg donation for IVF increases.
The debate about children receiving information on their biological parents is often couched in terms of rights – usually the parents' right to remain anonymous. But framing the argument in this manner is dangerously narrow and a more sensitive approach must be arrived at if untold confusion, mental anguish and even physical suffering are to be avoided.
Children need to know who their mothers and fathers are for their full well-being.