Your mother was sterile, but somehow managed to find a sealed genie. Hearing some stories she cracked the seal a little where the genie inside was able to look out into the world and asked "Why have you disturbed me?"
Your mother said "I heard that you granted a wish to whoever opened the box."
The genie asked "And what wish did you want?"
Your mother said "I wish I was pregnant!"
The genie said "Crack open the box a little further and i'll give you what you want." Your mother happy cracked open the box where the genie inside came out and forced a lot of his magic into your mother's womb where your soul went into. Your mother was gasping in pain and ecstasy as one of your mother's eggs was formed and the genie impregnated it. The genie said "Now then. Leave me alone." then went back into his box and slid the lid back on. A few months later you came out in a hospital. During the time you were in the hospital one or two people on the brink of death recovered somehow.
You were told that you were born a guy, but one time when your mother was changing your diaper she had said out loud after a sigh "I wish you were a girl... would make this a little easier on me." and then before she closed your diaper up she saw your dick suck into your body leaving a vagina. There were a bunch of other small changes, but she was happy with you being a girl and just let you stay a girl. However from then she started to notice whenever she would visibly say "I wish" her wish tended to be granted in some sort of way. As a little girl your mother just thought that you were being really nice with your cosmic powers, and didn't end up fearing you.
Then one day in a stroller walk there was a couple bickering angry with one another where one of them said "I wish you'd just die!" and then their partner just dropped dead. Your mother figured out that you couldn't actually control your wish granting and just granted the wish of anyone you heard.
Now you are five years old and legally required to start kindergarten. A bit concerned your mother...