It happened on a Wednesday. First information was gently inserted into everyone's mind, information about what would soon occur.
Going forward people between approximately the ages 18 and 25 would undergo a sort of second puberty: they would develop into fully functional hermaphrodites. The majority of people will have this hermaphrodation occur between 21 and 23, with only about 5% having it occur before 20.
For males this would take the form of developing breasts, loss of chest hair above the bottom of the rib cage, a slight widening of the pelvis and obviously the growth of a second reproductive system, a female one. This process generally takes six months, though breast development may continue sporadically well into one's late 20s.
For females, the main physical changes would be mainly limited to simply developing their male reproductive system, with few or no other visible changes. Development of the male reproductive system generally takes only three to four months for females.
These however are only the most common outcomes, and the tail of possibilities is long. For instance, it is entirely possible for example for a male to end up with an entirely feminine appearance by the end of this second major sexual development period. Or the opposite for some one born female, or anything in between. A person's desires can have an influence on this, so for example a closeted trans woman is more likely to end up with a feminine appearance. These outliers may take a year or more to fully change into their new appearance. Though the majority of people do follow the rules above.
The last thing that changes is sexual preferences, those attracted to men gain an interest in breasts on men. Everyone gains new urges and reflexes related to their new parts, and mostly gain an interest in the parts they were formally uninterested in. These are again generalisations, other outcomes are possible, rarely some may find their orientation changing, some may become bi, others may go from straight to gay, or the opposite, such cases would be rare.
Everyone ends up with a dual libido, that is, it is possible to be aroused with only one's male parts, or only one's female parts. In fact at some point their body will "lock in" to one or the other, releasing a pheromone signal that will cause their partner to "lock in" to the opposite. Once someone locks into female "mode", their male parts would pull almost entirely into their body to get them out of the way, much the same way they do in the cold.
The change that came was that everyone in the world would be altered as if this had always been the case, so those over 25 would all rapidly change into the hermaphroditic version of themselves, and those between 18 and 25 would land at some level of development of their new characteristics.
The warning given also included information that, at least in this initial change, people's relationships would be taken into account. So it would mostly avoid leaving those in love unattracted to their partner.
Brianna Adams sat outside at a cafe, waiting for her boyfriend to show up for their brunch before her first lecture of the day when the information hit her. She was at first stunned, unsure what to make of it, men growing boobs? And she was going to like them? Not only that but she would grow a... penis? She briefly toyed with the idea that it was some sort of weird delusion and she should call a doctor, but looking around she could tell
something
had happened to everyone. They were all reacting in their own ways. So at least everyone probably got the same weird information dump. Was it true? She couldn't bring herself to disbelieve it.
Her thoughts went in circles, and she watched the people around her, soon she saw her boyfriend, looking troubled, she called to him.
"HEY! Chris!"
He rushed over and joined her, "Ah, Bri, there you are... I... did you..."
"The thing about... boobs and..." she trailed off, "Yeah..."
"Ah."
"Not happy about the idea?"
"I... not especially... are you?"
"Well... not happy... I have to admit I'm... curious. Maybe I'll finally understand why some guys drool all over bigger girls, or why so many guys are obsessed with how big what's in their pants is."
"Mmm"
The barista brought their coffees and sandwiches out to them and set them down. As the door back into the cafe shut behind her it happened.
Brianna felt a strange sensation in her head, a feeling she couldn't pin down. Her panties rapidly filled, then overfilled. Her new balls didn't fit in the small area of fabric at the front. She found herself squirming uncomfortably. The sensations were strange, and some of them seemed to sort of overlap sensations from her original parts that were still there.
She blinked for a moment, looking at her food, then started looking up. Her gaze went from the table, up Chris' body, until it got to his chest where it stopped. She couldn't quite will herself to stop looking. Chris' chest had changed, his shirt was pulled taut over his new bust, large, round,
lovely
were the words that came to her mind. Her own breasts were modest, but Chris' could accurately be compared to melons. She felt... things. She was very much... finding it easy to understand how someone could talk to a chest. Then she felt something else. Her already over stuffed panties were tightening further as she got her first taste of male arousal.
His arms came up and crossed in front of his boobs.
"Hey, uh Bri?"
"Wha? Oh!" Her eyes came up to his face. "I'm sorry I... they... they're so big..."
"Yeah... I... guess you are getting that understanding... at least about boobs..."
She squirmed a bit and felt something move. Her new dick, it was no longer trying to push the front of her panties out, but was now sticking out of the leg hole. It still wasn't very comfortable. It felt strangely full. She could feel the weight of her skirt on it, pushing the tip down causing a pulling sensation down below it, around and behind her vagina. She managed to glance down at her lap. It was making a little tent, and still getting bigger.
"I... uh... don't think... I'll be... uhm too anxious about the other thing..."