Episode 1 of "DNA Lover" kicks off with So Jin's enchanting dream, where she envisions uncovering her soulmate through the intricate web of DNA analysis. But just as the veil of mystery is about to lift, revealing the chiseled features of her dream man, she jolts awake, leaving the tantalizing vision unfinished.
So Jin, a seasoned genetic researcher, has been down the treacherous path of love, her heart bruised by a string of men who betrayed her trust. Tired of the endless cycle of deceit, she yearns for a genuine connection. Yet, her latest heartache comes with a twist—her former beau, Sang-min, breaks things off, but surprisingly, this time without the sting of infidelity. His reason? A blunt admission that he never truly felt the spark, coupled with resentment that she sought to alter him, even crafting a DNA-customized serum to combat his balding woes. Stunned and disheartened, So Jin chases after him into the bustling streets, pleading for a reconsideration that never comes.
Meanwhile, we are introduced to Sim Yeon-u, an obstetrician-gynecologist whose love life mirrors a different kind of complexity. Engaged in a tumultuous romance with a younger woman, he finds himself at odds with her vibrant lifestyle, ultimately severing ties via a cold phone call. Yeon-u navigates dating with a clinical precision, his charm masking a tendency to cut ties at the slightest provocation. With his effortless good looks, he effortlessly skates through life, leaving a trail of subtly callous encounters in his wake.
As So Jin grapples with Sang-min's revelation—that he possesses the so-called "cheating gene"—she stubbornly refuses to believe he ever cheated on her personally, her trust in him, albeit misguided, remaining unshattered by any tangible proof. This unwavering denial underscores the depths of her emotional turmoil, as she struggles to reconcile the truth with her heart's desire for love untainted by deceit.
In the midst of it all, we cross paths with the heroic firefighter, Gang-hun, a man as kind-hearted as he is considerate, who consistently goes the extra mile to lend a helping hand. This particular evening, amidst the chaos of a raging fire, he selflessly offers his contact details to a distraught victim, unbeknownst to him that he had once rescued her from the brink of despair when she attempted to end her life. Fate smiled upon her this time, as her unconscious state revealed a joyous secret - she was carrying a new life within her.
Gang-hun, who happens to be So-jin's childhood companion, cannot help but feel a pang of concern for her unending string of heartaches. When So-jin extends an invitation for a nightcap, his gentle refusal leaves her a tad disappointed, yet resolute in her plan to seek solace at his family's cozy restaurant.
Inside the restaurant's warm embrace, So-jin encounters two women, each with a tale of woe. One, nursing a freshly broken heart at the hands of Yeon-u, seeks solace in alcohol's arms. The other, So-ri, merely a steadfast friend, accompanies her on this melancholy journey. As So-jin and Li-na share their mutual misery, a fire of determination ignites within them - they vow to teach Yeon-u a lesson he won't soon forget.
Fueled by liquor's bravado, they march unannounced into Yeon-u's abode, with Li-na demanding answers. Yeon-u, taken aback, mocks Li-na's accusations, dismissing her as nothing but a whiner. His callous words, particularly the denial of destiny's existence, push So-jin over the edge. In a fit of rage, she unleashes her makeshift weapon - a hair spray concocted for Sang-min - upon Yeon-u. Unfortunately, in his bid to protect his pride, Yeon-u sustains a cut, allowing the mysterious serum to seep into his wound.
With So-jin's rantings and spraying echoing through the air, So-ri swiftly spirits her friend away, leaving behind a forgotten serum and a single shoe as tokens of their unceremonious exit. Outside, So-jin turns to the heavens, pleading with the gods and sending forth beseeching signals, yearning for the man of her dreams to materialize. As they await a taxi's arrival, Gang-hun happens to pass by, bound for Yeon-u's place; their friendship, it seems, stretching back to a bygone era. Quick-thinking So-ri shields So-jin from Gang-hun's gaze, hurrying her back to safety before their paths could inadvertently cross.
Meanwhile, Gang-hun discovers Li-na, tears still streaming down her cheeks, perched at Yeon-u's abode. Yeon-u, with a sense of obligation, urges him to hail a taxi and ensure Li-na's safe departure. As they stand by the roadside, Gang-hun gently encourages Li-na to seek solace in the arms of a worthy suitor. Soon after, his patience wearing thin with Yeon-u's perceived callousness, Gang-hun confronts him for shattering women's hearts and storms off.
Dawn breaks, and Yeon-u awakens to a startling sight: one side of his sideburns has erupted into a forest of unwanted hair. The realization dawns on him that So-jin's serum has indeed wrought its miraculous, yet unintended, transformation. As for So-jin, her morning commences with a jumbled memory of the previous night's revelry. She dimly recalls her drunken wish for someone to sprout fur, but dismisses it as mere whimsy, agreeing to rendezvous with Gang-hun later in the evening.
Outside, fate brings So-jin face to face with Sang-min, his arm entwined with another. The betrayal hits her like a ton of bricks, yet she maintains her composure as he berates her. In a bold stroke, she reveals his genetic fate—a premature demise from diabetes, accompanied by imminent baldness. Sang-min's fury boils over, but Gang-hun's timely intervention halts his blow. He leads her to his father's restaurant, where the warmth of food and the tale of his parents' unwavering love serve as balm for her wounded heart.
Gang-hun, ever protective, issues a command to So-jin: bring any potential suitor to him for a thorough inspection. Despite the latest in a string of heartbreaks, So-jin remains steadfast in her quest for the one whose DNA echoes her own.
The next morning, Yeon-u awakens to find his sideburns have become an uncontrollable jungle. Despite his efforts to tame them with a razor, the hair grows back with alarming speed. Nevertheless, duty calls, and he must press on, stopping by So-jin's lab to collect his patient's test results. Little does he know, So-jin has already been informed of So-ri's meddling by her sister, and her surprise upon his arrival is palpable. The tension in the air thickens, setting the stage for a confrontation fraught with unspoken truths and unexpected consequences.
