World Expert On Fatherhood & Love: They're Lying About Monogamy & What Cheating Does To Your Brain!

She further clarifies the distinction between sexual monogamy—exclusive sexual relations with one partner—and social monogamy, where two people live together and raise children but may not be sexually exclusive. Dr. Machin points out that social monogamy is more common, but sexual monogamy is rare in the animal kingdom, including among humans. The imposition of monogamy, especially in Western societies, has been driven by cultural, religious, and legal controls designed to maintain social order, inheritance rights, and predictability in human behavior.

The Neuroscience of Attraction and Love

Delving into the brain’s role in love, Dr. Machin describes how attraction operates on both unconscious and conscious levels. Initially, the limbic system processes sensory information such as visual cues, scent, and body language to assess a potential partner’s biological market value—essentially their reproductive fitness. For example, women can unconsciously detect genetic compatibility through scent, specifically the major histocompatibility complex (MHC), which influences immune system diversity in offspring.

Once this unconscious evaluation triggers a positive response, the brain’s reward centers flood with dopamine and oxytocin, hormones that reduce fear and increase motivation to pursue the relationship. However, the conscious brain, particularly the prefrontal cortex, quickly evaluates social cues such as personality and behavior, which can override initial attraction. This complex interplay between unconscious drives and conscious judgment makes human love uniquely intricate compared to other mammals.

The Role and Importance of Fatherhood

One of the most groundbreaking aspects of Dr. Machin’s work is her focus on fatherhood, a subject often neglected or misunderstood. Contrary to cultural myths that portray fathers as dispensable or secondary caregivers, she emphasizes that fathers play a fundamental role in child development. This role is not limited to biological fathers but extends to any male figure who actively participates in a child’s life, including stepfathers, grandfathers, and mentors.

Fathers contribute uniquely by “scaffolding” a child’s entry into the social world beyond the family. While mothers provide nurturing and protection, fathers stimulate and challenge children, helping them develop resilience, social skills, and emotional regulation. This is often expressed through rough-and-tumble play, which fosters bonding and teaches reciprocity, empathy, and risk assessment. Dr. Machin highlights that fatherhood is evolutionarily rare and biologically supported by hormonal and brain changes in men, such as decreased testosterone and increased oxytocin, which prepare them for caregiving.

Changing Gender Roles and Relationship Dynamics

The podcast explores how shifting gender roles, particularly women’s increasing financial independence and educational attainment, are reshaping romantic relationships. Women today are less likely to prioritize marriage and childbearing as life goals, often valuing financial freedom and personal fulfillment instead. This individualistic approach contrasts with past collectivist societies where marriage was often a pragmatic necessity for survival and social acceptance.

Dr. Machin notes that this shift has led to a rise in singlehood, especially among women aged 25 to 44, and a higher rate of divorces initiated by women. The traditional model of monogamous heterosexual relationships is under strain as women reassess their needs and expectations, sometimes choosing to start fresh or forgo romantic partnerships altogether. This societal transformation calls for a reevaluation of how love and companionship are understood and practiced in modern times.

The Impact of Dating Apps and the Paradox of Choice

Dr. Machin critiques the modern dating landscape, particularly the role of dating apps, which have lowered the cost and effort of meeting potential partners but introduced new challenges. Unlike traditional dating, where meeting someone involved significant investment of time and energy, apps allow users to swipe and match with minimal commitment. This abundance of choice paradoxically makes decision-making harder and can lead to dissatisfaction despite numerous options.

She explains that the brain’s evolutionary mechanisms are not well-equipped to handle such vast pools of potential mates, leading to superficial judgments and a focus on minor “red flags” or “icks.” The lack of rich sensory information on apps hampers the brain’s natural attraction algorithms, often resulting in people going on many dates without forming meaningful connections. Dr. Machin suggests that dating apps function more as introduction tools rather than true venues for romantic engagement.

Polyamory, Monogamy, and Relationship Satisfaction

Addressing the contentious topic of relationship structures, Dr. Machin distinguishes between monogamy, open relationships, and polyamory. She emphasizes that polyamory—having multiple emotionally intimate and sexual relationships simultaneously—is often misunderstood and stigmatized. Polyamorous individuals argue that their approach is more honest and aligned with human evolutionary history, as it openly acknowledges multiple drives rather than concealing them.

Importantly, scientific studies show no significant difference in relationship satisfaction or well-being between people in monogamous and polyamorous relationships. The struggle with polyamory often lies in societal judgment and managing jealousy, rather than inherent incompatibility. Dr. Machin also notes that some people are genetically predisposed to be more comfortable with monogamy, but many others find it challenging, regardless of gender.

The Critical First Thousand Days of Child Development

Dr. Machin underscores the first thousand days of a child’s life as a critical window for brain development and attachment formation. Human babies are born extremely helpless due to evolutionary constraints related to bipedalism and brain size, requiring intensive caregiving. Both mother and father contribute uniquely during this period: mothers provide nurturing and biological care, while fathers stimulate and prepare the child for social engagement.

She stresses that fathers are vital from birth onward, not just after the child reaches toddlerhood. Early paternal involvement supports neural growth in the prefrontal cortex, which governs social cognition and emotional regulation. The complementary roles of mothers and fathers create a balanced environment essential for healthy development. Dr. Machin also highlights the adaptability of the human brain, noting that in non-traditional families, caregiving roles can be fulfilled by various adults, but the presence of both nurturing and stimulating figures remains crucial.

Biological and Psychological Changes in Fatherhood

The transition to fatherhood triggers profound hormonal and brain changes in men, preparing them for caregiving. Dr. Machin explains that testosterone levels drop significantly when men enter long-term relationships and drop further upon becoming fathers. This hormonal shift reduces competitive and mating behaviors, allowing bonding hormones like oxytocin and dopamine to take precedence.

These changes enhance emotional sensitivity, empathy, and motivation to care for the child. Men who actively engage with their infants experience faster psychological adjustment to fatherhood, while those who lack contact may not undergo these changes fully. Dr. Machin emphasizes that fatherhood is not an automatic biological state but one developed through interaction and caregiving, regardless of biological relation.

Attachment Styles and Their Influence on Relationships

Attachment theory is central to understanding how people form and maintain romantic relationships. Dr. Machin outlines four main attachment styles: secure, preoccupied (anxious), fearful avoidant, and dismissing avoidant. These styles are defined by levels of anxiety about abandonment and comfort with intimacy. Secure individuals balance independence and closeness, while insecure styles involve varying degrees of fear, avoidance, or ambivalence.

Attachment styles are shaped early in life by caregiving experiences and can evolve through relationships. Recognizing one’s own and a partner’s attachment style can improve empathy and communication, helping to navigate conflicts and emotional needs. Dr. Machin notes that modern society’s increasing individualism and digital isolation may be fostering more avoidant behaviors, complicating intimacy and connection.

Neurodiversity and Challenges in Love

Dr. Machin highlights the intersection between neurodiversity—conditions like ADHD and autism—and romantic relationships. The neurochemistry underlying love overlaps with that involved in neurodiverse conditions, affecting social cognition, emotional regulation, and sensory processing. For example, individuals with ADHD may exhibit impulsivity and novelty-seeking behaviors, which can complicate long-term relationship stability.

Masking, or the effort to conform to neurotypical social norms, adds stress and can hinder authentic communication in relationships. Neurodiverse individuals may struggle with empathy in ways that differ from neurotypical partners, requiring mutual understanding and adaptation. While some studies suggest higher rates of infidelity among adults with ADHD, Dr. Machin cautions against stigmatization and emphasizes the importance of education and support for all partners.

The Future of Love: Love Drugs and AI

Looking ahead, Dr. Machin discusses emerging technologies that could transform human relationships, including “love drugs” and artificial intelligence. Synthetic oxytocin and MDMA are being studied for their potential to enhance empathy, bonding, and relationship therapy. However, these substances raise ethical concerns, such as unintended side effects, dependency, and manipulation in abusive contexts.

Artificial intelligence, particularly chatbots and care robots, offers new forms of social interaction but cannot replicate the full neurobiological complexity of human love. Dr. Machin warns that while AI can support social skills or provide companionship, it lacks the capacity for biobehavioral synchrony—the physiological and emotional attunement fundamental to human bonding. She urges society to carefully consider the implications of integrating AI into intimate relationships.