Once he stepped out of the shower, and returned to the Chronivac, an idea popped into his head. "Y'know... I've always said I'd prefer Emily as a boy..."
He checked the chronivac, and he realized he could make this a reality. "Ah, Sweet!" He clicked on the gender field, replacing the "Female" value with "Male".
As he ran down to watch it, he was almost too slow. The changes took effect almost instantly, looking over to where his sister was. Her long, dirty blonde hair shrinks back into her head, leaving it short but still remaining slightly feminine.
As she transformed, she gained a slight bit of her height back, but the clothes that (s)he was wearing remained unchanged on him. Jeff knew the main differentiating change was hidden by Emily's skirt, knowing that at that age the genders were pretty similar beyond that.
Seconds prior, Jeff was looking at his little sister, Emily... and now, he was looking at his new little brother, sitting content on the couch.
He never shifted anything else, so his brother still had the name Emily, and kept the same girly personality. "Guess he's a tomgirl, now..." Jeff was happy having Emily as his brother, rather than his sister, but wondered if he should adjust him to be more like a boy.