Only daughter who cared for widowed mother for 20 years stunned to find half-sibling on inheritance documents

A woman who spent 20 years caring for her widowed mother — including nursing her through illness — has expressed feelings of betrayal after discovering a half-sibling listed on inheritance documents following her mother's recent death.

The story of A, a housewife in her 60s who had believed her entire life that she was an only child, was featured Friday on YTN Radio's "Jo In-seop's Legal Consultation."

"After my father passed away 20 years ago, I was the one who lived with and looked after my mother the whole time," A said. "My mother fought a grueling battle with cancer for years and passed away not long ago. I was trying to sort out the inheritance after the funeral when an unimaginable problem came up."

Her mother had owned a building, but when A checked the family relations certificate, she found someone else registered alongside her.

"I assumed I would inherit everything on my own since I was an only child," A said. "At first I thought there was a mistake in the government records." Searching her memory, she recalled relatives mentioning when she was young that her father had fathered a child through an affair. After asking family members, she learned that her father had insisted on registering the half-sibling in the family registry as his legitimate child.

"Someone I have never once met in my life is about to take half of my mother's estate simply because the paperwork says they are a child," A said. "I can't sleep at night from the injustice of it. I'm also overwhelmed by resentment and a sense of betrayal toward my late father."

She added: "This person never showed their face while my father was alive, and not even at the moment my mother passed away. Do I really have to hand over half the estate to someone like that?"

Attorney Ryu Hyeon-ju said the deceased in this case is the mother, and strictly speaking the half-sibling is not the mother's biological child and therefore has no inheritance rights. "However, because the half-sibling is registered as the mother's child in official records, A will need to file a lawsuit — a suit to confirm the absence of a biological parent-child relationship — to have that corrected," Ryu said.

Ryu explained that such a suit can be filed not only by the direct parties to the biological relationship — the father, mother or child — but also by any "interested party." "A person whose rights are infringed upon by an inaccurate entry in the family relations register can also bring the action," she said.

If a court ruling confirms that no biological parent-child relationship exists between A's mother and the half-sibling, the legal tie between them would be extinguished retroactively, the entry in the family relations register would be struck, and the half-sibling would automatically be excluded from the list of heirs, Ryu said.

Ryu also noted that even someone who is not a biological child can be recognized as an heir through adoption, provided certain conditions are met — including that both parties consented to the adoption, that a legal guardian's approval was obtained if the adoptee was under 15, that the adoptee was not older than the adoptive parents, and that the relationship involved actual caregiving and a shared family lifestyle. If those requirements are satisfied, the adoptee holds the same legal standing as a biological child, and a suit to deny the biological relationship would not succeed, she said.

"In this case, the person said she never once saw the half-sibling while growing up, which suggests there was no caregiving or shared family lifestyle whatsoever," Ryu added. "The substantive requirements for adoption do not appear to have been met, so I believe the suit to confirm the absence of a biological parent-child relationship is likely to succeed."