In the year 2000, 19,000 children and their families joined a landmark research project – the Millennium Cohort Study (MCS). This longitudinal study has played a vital role in helping us track trends for children growing up in the early 21st century. This year, the Institute for Fiscal Studies published an analysis of the MCS cohort indicating that 44% of children born in 2000-2001 will not have lived with both their biological parents throughout their childhood. This compares to a figure of 21% for those participating in the 1970 British Cohort Study.

As a signal of change, this should spark a deeper conversation about who “does” parenting in our society – along with the implications for those whose work involves children and families. It points to an important shift in children’s lived experiences, one which has been underway for some time. Yet, when it comes to building up a more detailed picture, the information we have about family structure is still relatively limited. The Nuffield Foundation has commented that “our principal sources of data no longer reflect the reality of modern family life in the UK”.

The picture may be incomplete, but there are some sources of insight into the range of adults who are involved in children’s lives, beyond biological parents. In 2011, 180,000 children under 18 were estimated to be living with a relative or family friend in kinship care, while about a quarter of pre-school children in England received childcare from grandparents in 2021. In recent decades, widening access to reproductive technologies such as IVF, surrogacy and egg donation have given rise to new family forms and models of kinship. Changes in legal definitions of parenthood have followed. For example, as of 2009, the ‘non birth mother’ in a lesbian couple could be named as the other parent on a birth certificate if the couple conceived together through donor insemination or IVF.

A wide cross-section of adults are likely to find themselves in a parenting-type role at some point, whether through a new partner, as an adoptive or foster parent or in a less formalised role. These are not the family structures for which many of our policies and services were designed, which leads to the risk that caregivers who would benefit from support are being overlooked or inadvertently excluded.

Historically, fathers have often been absent from early years research, services and data, an omission that is beginning to be better addressed through initiatives such as DadPad. Should we now start asking if there are additional hidden figures in children’s lives? And whether we are missing opportunities to support other people playing a key role in children’s development?

One thing is clear: in any family structure it’s the quality of relationships that matters for children’s development, particularly with key carers. Secure attachment with a caregiver and warm and responsive adult-child relationships make a difference to children’s social, emotional and cognitive development and later outcomes. Relationships matter in other ways too: parents’ mental health affects children and access to social networks matter for everyone in the family.

Many family services are increasingly focusing on relationships, both between parents and children and between the parents themselves. Other ways in which we could respond to this signal could include specialist interventions that work with different adults taking on parenting roles, alongside approaches to intelligence and data-gathering that focus on understanding who matters in children’s lives. More inclusive and participatory approaches in research and service design would help to ensure that we are really listening to and understanding families, leading to more responsive support.

Some innovations are addressing the changing nature of families and households. Shared Lives Plus, for example, showed us that we can think creatively about how we support both relationships and the needs within different homes when they matched young people seeking accommodation with elderly people with room to spare. Nesta in Wales worked with Flintshire County Council to adapt the Mockingbird Family Model to create extended families around foster children and carers.

And, if more of us are going to play a parenting role, whether as a biological parent or a temporary carer, can we be better prepared? What if we got ahead of the curve and made sure that we’re all schooled in key aspects of child development, such as attachment theory, or even how to get the most out of play or sharing a story book?

The fact that families are changing shouldn’t be a surprise. The last few hundred years provide us with plenty of examples of how attitudes and practices can change – from wet nurses and governesses and “seen and not heard” to an increasing emphasis on children’s rights and voices.

So perhaps this signal is really a reminder of what we have always known – “parenting” is a process and a relationship, rather than a fixed role. We need to think about the whole ecosystem of adults who have the potential to positively influence children’s lives, investing in the quality of relationships first and foremost and creating a culture that genuinely supports everyone involved in parenting.