In searching for the balance between giving and self-protection, we arrived at a reality I consider fundamental: in every relationship, influence flows in both directions, always, whether we are aware of it or not. There is no relationship in which one person influences and the other is influenced. There are only different degrees of awareness of a process that is always bilateral and always active.

This perspective changes something essential in the way we view relationships. If influence is reciprocal and continuous, then we can never be mere spectators or passive victims of the dynamics between us and others. We are active participants, even when we believe we are neutral or simply reacting.

The relational system as a living organism

Murray Bowen, the psychiatrist who developed family systems theory, described the family not as a collection of separate individuals but as an emotional system in which each element affects every other element. Any change in one part of the system produces changes in all the other parts. The anxiety of one member propagates through the entire system. The growth of one individual disturbs the equilibrium of the whole group.

This logic applies not only to families. It applies to every significant relationship: the couple, the long-term friendship, the professional team, any human configuration in which people interact repeatedly and with emotional stakes.

The practical implication is significant: when something is not working in a relationship, the explanation rarely lies entirely on one side. Dysfunctional dynamics are co-created, not produced unilaterally. Not because fault is equal or because responsibilities are identical, but because each person in the system contributes, through their behaviour, to either perpetuating or transforming the dynamic.

How we shape each other without realising it

Mutual influence operates at several levels simultaneously, and not all of them are visible.

At the most surface level, influence is behavioural: you react to what the other person does, they react to what you do, and the cycle continues. If a partner becomes distant, you become anxious and seek more closeness. Your anxiety makes them withdraw further. Their withdrawal intensifies your anxiety. Neither consciously chose this dance, but both are dancing it.

At a deeper level, influence is cognitive: the way someone sees you gradually shapes the way you see yourself. Research in social psychology has demonstrated the phenomenon known as "interpersonal self-fulfilling prophecy": if someone in your life consistently treats you as competent and capable, you will tend to become more competent and capable in the context of that relationship. Conversely, if you are consistently treated as fragile or incompetent, you may come to internalise and express precisely that fragility.

This is a responsibility few people consciously own: the way you see the other person shapes them. Your expectations of them contribute to who they become in relation to you.

At the deepest level, influence is identity-forming: in long and meaningful relationships, we partially construct the self in dialogue with the other. We don't simply adopt their values or behaviours; we also define ourselves in relation to our differences from them. Who you are in relation to your partner, your family, your close friends is partly a product of these relationships, not purely an expression of a pre-relational self.

Mutual influence in couples: the unconscious dance

Of all relationships, the couple is the place where mutual influence is densest and, often, least acknowledged. Two people who live together and invest emotionally in each other calibrate each other continuously, at the level of biological rhythms, emotional states, values and vision of the world.

Research in chronobiology has shown that partners who live together end up synchronising their circadian rhythms. More recent studies have demonstrated that heart rate and breathing rhythm also synchronise in intimate interactions. We are, literally, biological systems that regulate each other.

At an emotional level, couples develop patterns of emotional regulation that are co-constructed. If one partner is calm and stable, the other will tend to regulate towards that stability. If one brings chronic anxiety into the relationship, the other will be constantly emotionally taxed, regardless of their own state.

One of the things I find fascinating, and slightly humbling, about this reciprocity is that intention is not required in order to influence. You don't need to want to change someone in order to change them. Your presence, with everything you bring with you, is already shaping them.

Why awareness of mutual influence matters

There is an enormous difference between being an unconscious participant in mutual influence and being a conscious one. The first allows the relational dynamic to unfold on autopilot, driven by patterns, unresolved histories and reflexive reactions. The second introduces the possibility of choice.

Awareness that you influence and are influenced in equal measure brings with it a few valuable questions: How do you contribute, through your behaviour and your way of being, to the dynamics you experience in your relationships? What patterns do you bring repeatedly from relationship to relationship? Where are you a regulating and stabilising factor in the lives of those around you? And where are you, without meaning to be, a source of destabilisation?

These questions are not comfortable. But they are, in my view, among the most productive you can ask about your relational life.

Positive influence as a deliberate choice

If influence is inevitable, then the choice is not whether you influence, but how. And that opens a territory I find both challenging and encouraging.

You can choose to be a stabilising presence in your relationships, not by taking on others' problems or by sacrificing yourself, but by managing your own emotions well enough that your presence is, in general, a factor of calm rather than anxiety. You can choose to project onto the other person an image that allows them to become more, not less. You can choose to enter interactions with a genuine intention to contribute something positive, not only to meet your own needs.

This is not idealism. It is a pragmatic understanding of the fact that in interconnected systems, what you bring returns to you, not necessarily immediately and not necessarily from the same source, but it returns. Relationships in which both people bring the awareness of the positive influence they can exert are, invariably, healthier, more resilient and more satisfying relationships for both of them.

Mutual influence is not a threat. It is the reality in which we live as social beings. Understanding it is the first step towards using it responsibly, for your own benefit and for the benefit of those with whom you are in relationship.

Think of the most significant relationship in your life right now. How has it shaped you over the past year? And, equally important, how have you shaped it? What did you bring that helped, and what did you bring that made things harder?