Confusing blood group results and ‘infidelity’.


Derin sat on the sofa, swirling the wine around in his cup. His mind was deep in thought as he waited for his wife to get back home; they had scores to settle.

Moments later, she walked in, obviously tired, but glad to be home. “Thank God it’s Friday!” she said with glee, lifting her hands above her head in celebration. Imade was still looking sharp in her light grey trouser suit and hot pink heels.

‘She always looks good.’ Derin thought but quickly called himself to order. ‘You need to focus Derin, You’re already getting distracted.’ he told himself. Adjusting himself to face her, he asked, “Where are you coming from Imade?”

 “Ummmh…from work of course. Is there somewhere else you expect me to be coming from?” Imade replied as she sat down on the sofa near him.

“No. Nowhere else.”

“So why are you asking your tired wife such a question? Or do you have plans for me?” she asked teasingly.

“Is Imaobong really my child?”

“I’m sorry?” Imade said, sitting upright. She looked at his face to determine if he was pulling her legs but he looked very serious. “What did you say Derin?”

“You heard me.” he replied emotionlessly.

While he waited for her response, Derin replayed the events that led up to this in his mind.

He had taken his daughter, Imaobong, for a blood test to determine her genotype and blood group, and was shocked to see her results as blood group: O positive, and genotype: AC. Derin was very sure that both his blood group and Imade’s was A positive because they had tested it together over fifteen years ago while dating. His genotype was AA while hers was AS.

Blood samples to determine blood group and genotype
Photo by Karolina Grabowska from Pexels

Derin confidently asked them to repeat his daughter’s test; same result. Then, he asked them to run his and his results were what he had always known.

Something was definitely fishy. Did their eleven-year struggle with infertility make Imade get pregnant for someone else? He tried to wave it aside but it just wasn’t adding up.

“Is Imaobong really my child?” he repeated, coming back to the present.

“Babe, if this is a joke please stop it now.” Imade said, very much confused.

“A joke? Not at all. Imaobong’s genotype is AC whereas I’m AA and you’re AS. And how come her blood group is O positive and both of us are A positive? Have you ever seen a lion giving birth to a goat?”

“I don’t know Derin.”

“How can you not know? You gave birth to her! I just need to be sure it was through me.”

“Derin, what exactly are you saying? Are you insinuating that…?”

“I’m not insinuating anything Imade. Just answer me.” he replied. He was already getting impatient.

“My God! What has come over you? If there’s something you want to say, just say it and stop all these accusations.”

“Woman, I didn’t accuse you! I only asked a question!” Derin said. He stood up in anger, spilling his glass of wine.

Wine spilled in anger over blood group and genotype misunderstanding
Photo by Polina Tankilevitch from Pexels

Imade was dumbstruck for a full minute. When she eventually found her voice, she said “Imaobong is your child.” Then she picked up her bag and walked out of the living room.

Derin sat down in frustration. This tension was exactly what he was trying to avoid. But the possibility that Imaobong wasn’t his child still gnawed at him.

He called Ntike his friend and narrated the whole story. “Why don’t you repeat your wife’s test and give her the benefit of a doubt?” Ntike said.

Amazing! Derin had been so blinded by suspicion that he hadn’t thought about that. He went up to meet her.

“Imade, I’m sorry. I think we should repeat your test tomorrow…”

“Whatever.” She said turning her back on him.

Early the next morning they went to the laboratory. Imade hadn’t said a word since their clash yesterday. However, when her result came out as genotype: AC and blood group: A positive, she confronted the laboratory staff. “I think you’ve made a mistake.” she said.

“Yes! Run it again.” Derin added. He was already feeling silly with the turn of events but he consoled himself with the thought that Imaobong’s blood group still didn’t match.

After much back and forth with the laboratory staff, Derin and Imade were referred to the in-house doctor for further explanation.

“Actually, some genotype testing methods inaccurately label a C genotype pattern as S, or occassionally as A. This is why it’s advised to test your genotype in at least two laboratories. However, using improved genotype testing methods such as HPLC or IEF like we do here, drastically reduces these mistakes.” the doctor said.

Photo by Daniela Holzer on Unsplash

“Ok. I can accept that, but how come my daughter’s blood group is O and we are both A?” Derin asked.

The doctor smiled. “I see this all the time.” he said.

“You see, all a person’s physical characteristics are determined by his or her genes and these genes come in twos, because we get one from our father and the other from our mother.

For the genotype result, you can see that it is represented by two letters which mirror what is found on the gene. Yours is AA while your wife and daughter are AC; one from dad and the other from mum. But for blood groups, the result is not always written in twos. You can have A, B, O or AB and the reason for it is quite simple.

Whenever a person inherits an O gene together with the A or B gene, the O gene does not manifest in the person’s traits. Instead the A or B run the show. In other words, A and B dominate over O, so we say A and B are dominant. So if a person inherits A and O, his blood type manifests as A, which is dominant. Same for B and O. However, if someone inherits an A and a B, they manifest together leading to blood group AB because they are equal partners, and equal in dominance.

So, Derin, your blood group is A, but your genes may actually be AO. Your wife’s blood group is also A but her genes may be AO. If that is the case and both of you passed the O gene to your daughter, her genes would be OO and therefore her blood group would be O.”

“Oh… I see.” Derin replied in a low tone, realising that his impatience had made him suspect and accuse his wife falsely.

Imade sighed. “Thank you doctor.” she said. She left the consulting room without a word to Derin.

The doctor smiled knowingly. “Derin, it seems to me that you have scores to settle with your wife.”

“Indeed I do. Thanks doc.” he replied and walked out to go save his marriage.


IEF- Isoelectric Focusing, a very sensitive method for determining genotype.

HPLC- High Power Liquid Chromatography, a very sensitive method for determining genotype.

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16 thoughts on “Confusing blood group results and ‘infidelity’.”

  1. Michael Adetola Adeyemi

    This is highly educative. It is quite clear that
    Biology taught in the Secondary School on the topic: blood group – is dangerously over-summarized. Couples need to know this and should always seek for more information before ignorance is allowed to ruin their marriage.
    Thanks for introducing the “intermediate” level information on this subject.

    1. 😂😂😂 Dangerously oversummarized had me laughing.
      Yes, it’s crucial to seek information from the right sources before jumping to conclusions.
      And you’re welcome!

  2. Thanks for sharing your knowledge.
    This is a great teaching and an eye-opener. I suggest that this teaching/knowledge should be included in the pre-marrital counseling for young people who are getting ready for marriage.
    Thanks again. God bless you.

  3. Dr Ayobami, dishing out stuff in a very Interesting, easy to follow manner. Thanks for all you do. Great piece and aptly put too

  4. Yetunde Oyeleke

    Thanks for this doc. Had the same issue with my son. His blood group is different from me and my husband’s blood group.

  5. This piece on blood group and genotype is so insightful.
    Sincerely, it needs to be included in marriage counselling programme.
    Thank you Doc!

  6. “Dangerously oversummarised” quite captures it sir.
    Sadly, that’s the only “knowledge” of blood tissue typing many will ever have pre-marriage. A little knowledge is rathef an awful thing

    Thanks Dr Folayan for your akitiyan (pun intended😉😅)

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