“Found in the estate papers,” she said. “Turns out Ana wasn’t AB at all. She was O negative her whole life. The AB was a transcription error made decades ago.”
“That’s your lab task,” Dr. Reeves smiled. “Using only the pedigree and a fresh blood sample from Julian, determine if he could be Ana’s son—and whether the estate should accept or reject his claim.”
Dr. Reeves handed them a sealed evidence bag. Inside: a worn hospital wristband labeled lab activity blood type pedigree mystery
The late afternoon light slanted through the lab windows as Maya pinned the last pedigree chart to the corkboard. “Okay, team,” she announced, uncapping a set of blood typing trays. “This is the Martinez family case.”
Silence. Then Priya, the group’s quietest member, spoke up. “That changes everything. Two type A parents can have a type O child. But an A and an AB cannot produce a type O child. Ever.” “Found in the estate papers,” she said
“But here’s the twist,” Dr. Reeves said. “Carlos is not the father.”
“But that’s not the only clue,” Dr. Reeves added. “Carlos’s blood type was confirmed type A—but Ana’s medical record from decades ago shows she was typed as type AB.” The AB was a transcription error made decades ago
Her partner Leo leaned in. On the chart: Grandparents Ana and Carlos (both type A), their three children—Elena (type O), Marco (type AB), and Luis (type A)—and Luis’s two kids, Sofia (type A) and Diego (type B).