Three things have made me check my commitment to adoption this week. The first was the release of a major Hollywood movie, the second was an apology from the Catholic Church and the third was a conversation with a 34-year-old grandmother.

The Light Between Oceans hit cinemas this week. I won't be spoiling the ending for you, but it begins with a young couple living alone on an isolated lighthouse station burying their third miscarried baby. As the woman grieves by the graveside a rowing boat is discovered on the shore. The boat contains the body of a dead man and a living baby, barely weeks old. It seems as though their prayers have been answered. God has sent them the child they have been longing for. They raise the child as their own until, on a rare trip back to the mainland, they discover the child's birth mother. The young woman lost her husband and her daughter while trying to escape from xenophobic abuse and despite her depression is still hoping they will be found. What should the lighthouse parents do? Whom does the child belong to? What is in its best interests?

The film boasts an impressive cast including Oscar winners Alicia Vikander and Rachel Weisz and Oscar-nominated Michael Fassbender. I'm not sure I can face the movie, as even reading the book made me cry uncontrollably (as my fellow passengers on the British Airways flight can testify). It's a gripping, emotionally rich read. The story draws you into the pain of a couple wrestling with infertility and desperately wanting a baby, as well as the pain of a mother who has lost hers.

It offers an unusual angle on the issues around adoption. Naturally, we are drawn to sympathise with the lead characters as we see the world through their eyes. We identify with the emotional torment of a family facing the possibility of relinquishing the child in their care.

As a foster carer, I sympathise with the couple at many levels. I have looked after children whose origins were with another family and who will potentially return to that family, or be adopted by a new family. I understand the fierce sense of protection for a child that has ended up in my care. I understand the terrible pain of worrying when and how the child may be removed from my care. I have also seen the awful wrench as children are taken from their birth parents and the deep-seated and long-lasting pain that causes, and so I also feel for the birth mother in this story. The book explores these issues brilliantly. The strongest message that is demonstrated by the film is the public understanding that you can come to love a child that you are not biologically connected to as your own child. This is the reason why the book has sold millions and why Hollywood has turned it into a major production.

However, I also struggle with the initial premise of the film and the selfish decision made right at the beginning to claim a child for their own without any concern to find out where she has come from. They are committing a criminal act. No matter how much they love the child, legally they have no rights over her. Similarly, although a foster carer may love the children in their care as if they were their own flesh and blood, it is the legal process that decides whether they are to be reunited with their birth families or to be adopted and by whom.

The Light Between Oceans was released the same week that the head of the Catholic Church in England and Wales gave a formal apology for the forced adoptions of the babies of young women who were pressurised into relinquishing their children. Somewhere in the region of half a million children were adopted during a 30-year period where people representing Catholic and, to a lesser degree, the Anglican Church-based adoption agencies put undue pressure on unmarried mothers to give up their children. This issue was in the public eye recently through the film Philomena, starring Dame Judy Dench. And an ITV documentary, Breaking the Silence: Britain's Adoption Scandal has also been aired following the stories of some of the families involved. The culture has moved a long way since the days where there was a significant amount of social shame around pregnancy outside of marriage, and adoptions were managed mainly through Church-based agencies. Cardinal Vincent Nichols, the head of the Catholic Church in England and Wales, apologised for the Church's role, saying: "The practices of all adoption agencies, whether religious, charitable or state, reflected these attitudes and were sometimes lacking in care and sensitivity. We apologise for the hurt caused by agencies acting in the name of the Catholic Church."

What both the fictitious Light Between Oceans and the real historical incidence of forced adoption highlight is the terrible toll losing a child has on the birth mother. This anguish cannot be underestimated. The idea that women who wanted to raise their children and who were perfectly capable of raising their children should have those children removed from them by emotional pressure or by lies and deception is unconscionable. It is important that these public sins are confronted. There was a profound injustice that women who became pregnant out of wedlock faced judgment, while the men involved faced no or little consequences. And to make the assumption that because a woman was single she was incapable of raising a child is also profoundly unjust.

However, the injustice of the removal does not mean that the children did anything wrong. Nor does it mean that the adopters did anything wrong, either. Indeed, many of them did a brilliant job of raising children who were profoundly loved as if they were their own birth children.

In those days, adopters often thought they were being given relinquished children, with little or no understanding of the pressures on the birth mothers. Adoption has moved a long way since those difficult times. The vast majority of children available for adoption today have been victims of neglect or abuse. Most of the time their birth parents are unable to learn basic parenting skills of putting the needs of their children above their own, often because they too are victims of neglect or abuse. The vast majority of children waiting to be adopted in the UK are not babies but older children, often with additional needs and very often along with their brothers and sisters who need new families to take them in. And currently in the UK there are more children waiting for homes than adoptive families willing to care for them.

I was challenged by this recently when I was in Kiev, Ukraine. I met Oleg and Raya, foster carers for children transitioning from orphanages into wider society. When one of their foster children turned 17, Oleg and Raya offered to adopt her so that she would have a permanent family in her life. Oleg was 34 years old and his wife was 27 at this point. But Oleg reflected: "This was the right thing to do, we had been talking about adoption for a long time so that children would have some permanency. We understood that if it was a legal process it would mean more to her and she would know for sure that she was part of our family." Raya explained: "I really wanted to give our daughter a permanent standing, God adopted us and gave us security. I wanted her to have a forever family. People think only young children need family. But I understood even at 27 that I still needed my parents to be there for me and I wanted her to have the same." Now, seven years on, their adopted daughter is a mum herself, and Raya, aged only 34, is a proud grandmother.

There are currently 100,000 children living in orphanages in Ukraine and organisations like Ukraine Without Orphans are working to empty the orphanages and help children to be looked after in a family context through adoption and foster care.

Both the UK and the Ukraine have come a long way from their shameful past when it comes to children in care. As a nation the UK is committed to no longer forcing unmarried women to relinquish a child. In the Ukraine, they are committed to no longer abandoning children in under-resourced institutional orphanages. Perhaps it is time for us to rethink adoption too. It is not the last resort for people desperate to have a child but whose biology prevents them. It is not a secretive, deceptive mechanism of severing children from their birth families. It is about discovering what is best for the child involved. It is about securing for each child who has lost a family through no fault of their own, a new family that can meet their needs, pour love into their lives and give them a place they can belong forever. Adoption is "building a family through the process of concentrated, dedicated, enduring love rather than biology".

Dr Krish Kandiah is the founding director for the adoption and fostering charity Home for Good. www.homeforgood.org.uk