“A regression, in clinical terms, is where we psychologically revert to an earlier stage of development,” says Mark Vahrmeyer, psychotherapist and spokesperson for the UK Council for Psychotherapy (UKCP). “The theory posits that infantile states of development are, at least for the vast majority of us, not fully outgrown and therefore when we are experiencing high levels of anxiety, regression can be something that happens to us as a form of defence against the powerful feelings.”

So, however much we’ve grown up, our old behaviours might still be there below the surface, and it’s high-pressure situations like Christmas, where expectations and emotions run high, that bring them out. “There’s no delete button in our brain,” adds counsellor Juulia Karlstedt. “As we change and grow we lay new neural pathways on top of old ones. It is easy to choose those new ways of behaving in low-stress situations and becomes increasingly difficult the more stress we find ourselves under. Essentially, during stressful situations, our brain goes on autopilot and chooses the neural pathway that is most established for the situation we find ourselves in.”

As our family dynamics have played out for decades, they are “very deeply rooted” neural pathways in our brains, Karlstedt explains. Plus, often the dynamic is managed by everyone in the family playing a specific role “Even as adults, our parents can sometimes continue to talk and interact with our ‘inner child’ and we can, in turn, end up reacting from that childlike place.” This isn’t always necessarily a bad thing; sometimes it can be “nurturing and nostalgic”, but it can also, Karlstedt says, remind us of dynamics that were hurtful or take us back to a rebellious childlike space, while our parents might connect with their inner disciplinarian. Cue clashes.

Why do we regress to our teenage selves when we come home for Christmas – and what can we do about it?