A small change
In one universe, Uchiha Madara was born a boy and in another one a girl, all thanks to a meiosis error. In one universe, he got one X chromosome from his mother and one Y chromosome from his father but in other universe Madara got an additional X chromosome from his mother.
As the other embryo begin to divide in order to survive it lost its Y chromosome and so uniparental disomy occurred.
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In a very cold winter, near the end of December, earth was coated by layers upon layers of snow. No planets were in sight and all trees were barred; a woman was giving birth.
Inside one of central houses of many identical houses, a man was pacing franticly in front of a door. His face was completely blank but sudden twitching of his fingers gave away his worries. 'Why won't it end?' The thought was repeating in his mind over and over again.
From that inside heart wrenching cries could be heard. Inside that oak door were two women one young and other old. One was laying spread eagle on futon. Of course it was the young one; old women don't go into labor after all.
The wrinkled old woman was urging the other to push. Her head between her legs, she said hoarsely "only a little more. head is out. come on stop being so weak.)) It was obvious that the old woman's bedside manner needed some serious work. Her obligation to sit there for hours had helped it neither.
Young women doubled her efforts. She too was tired of her company and pain; especially the company. She just wanted this to be over and to sleep few days straight, so she collected all her remaining strength and cried out giving a final push. Finally a baby's cry filled the room.
Woman collapsed on futon. No power was left in her body. Midwife took the baby -not paying any attention to wife- to the other side of room to wash in basin and warp in a blanket.
The man, tajima rushed in after hearing the baby's cry without waiting for permission. As he saw the midwife busy cleaning and clothing the baby he went to his wife to help her get dressed and comfortably half raised with pillows baking her up.
Pale, black haired woman swatted her sweaty hair out of her face to behind her ears, then holding her hands out she said with sudden surge of power "my baby, give him to me."
Midwife compelled and placed the blanket covered baby in mother's outstretched arms; of course not without muttering under her breath something about ungrateful brats. Younger woman was too happy to pay her any mind.
She gazed longingly at her baby, and said "Madara, his name would be Madara." Then she glared heatedly at her husband daring him to protest. He did not. He was not idiot enough to argue with his wife after such a hard labor. Not if he wanted to have another child. 'Besides' he thought smugly 'It's still three to one in my favor'
He put one hand on his wife's shoulder to comfort her. She leaned against him. He cupped other hand around baby's face. 'It's better to just enjoy the moment' he thought. The cold clutch of fear was beginning to release him. 'Thank God they are both fine.' They Both felt oddly content.
Midwife decided to speak "tajima-sama, please forgive me for intruding, but the baby is a girl.)) and so the bubble of happiness shattered.
"What" exclaimed father. Mother quickly checked baby's gender. "It's true. it's a girl! I thought it would be boy! Her name… what would it be?" She shook her head trying to clear it to no value.
Unlike his wife the husband quickly put himself together. His eyes changed into sharingan and then the midwife was dead. It was obvious their reasons for going into shock, differed greatly.
Wife gasped "tajima-san, what are you doing?" She wasn't feeling sad about midwife; no not at all. But his reaction after hearing her child's gender worried her to no end. He turned to her "I'm protecting my daughter" Was his cold reply.
She shook her head hard "can you hear yourself? You aren't making any sense. Protecting her with killing the midwife? Have you lost it?" He came closer to her, eyes cold and calculating but thankfully black. She draws Madara to her bosom as she found herself freaked out.
He gripes her shoulders and looks at her eye to eye and says urgently with a bit of pleading mixed in "think woman, think." she stars uncomprehendingly and even more freaked out at her husband. She glances out of corner of her eyes at limb body at floor.
As he understand she can't comprehend, he sighs aloud, draws back his hands and brushes back his hair then he begin explaining "you know that main family usually bear only boys?"
She frowned and said nearly fuming "yes, but if you dare…" he holds up a hand and she fall silent. Madara who was long sleep, stirred in her arms after feeling her rigidity but fortunately stayed sleep.
Husband said "no interrupting until I'm finished." she nodded uneasily. So he continued "mostly when sharingan is inherited it would be inclined to mother side as you know." she nodded "yes, I know. in cases that father is the only uchiha parent, he can only pass it on to his daughters as a dormant condition that can only be awaked in next generation."
He nodded. "Yes quite right. But let's not get diverted. We are both uchiha." She nodded and gestured for him to continue. "A child's sharingan's power is closer to mother than father, and because of that clan head or hair always marries the strongest kunoichi or a woman with strongest sibling." She begun to understand. She hold her breath, dreading next sentences. "Now tell me woman" he focused his intense gaze on her "if there is a girl with main family's blood in her vain, how do you think others will react?"
She trembled as her imagination answered the question. She draws Madara closer to herself and stared at her round face with dark black hair ornamenting it. Said with shaking voice "They would be like a pack of wolfs fighting over meat." She smiled bitterly "all of them would want to have her as their bride, for sake of stronger grandchild." she clenched her fists.
Tajima nodded gravely "yes, they would. last time a girl was born she was imprisoned in name of her own safety and for her hand in marriage nearly a civil war was broke out in clan."
"No" she chocked, her face losing color "I didn't go through all that trouble to give birth to her just to see her in hell" She grabbed a fist full of his yukata pulling him close "you have to do something. I want my child to be free. "
He uncurled her fist and placed it back around the baby then he gazed at baby, gently touched her face. His face turned soft for a second.
As he looked up to meet his wife's tearful gaze; He said "I know. That is why I had to silence the midwife." His eyes turned icy cold "Today no girl was born. You give birth to another boy and we named him, Madara"
She wiped clean her tears straightened her back and said without a single doubt "yes, our boys would be excited to have a little brother"
And thus, first blood was spilled to protect their baby's secret.