After hitting save, Jeff watched as the profile pictures in his family tree shifted and morphed into their new forms.
His great great great grandfather became a giant of a man. According to his profile, in his prime he was 6'5" and just over 300 lbs of muscle. His great great great grandmother's profile showed a woman of amazonian proportions, taller and more muscular than a vast majority of men, but still retaining a curvaceous figure. The two of them side by side was a sight to behold, even on the Chronivac's screen. Their profiles even stated that they were at one point a strongman/strongwoman sideshow in the 1800s, a fact that Jeff now realized he had tucked in the back of his mind as a bit of family trivia.
From there, Jeff watched as the changes trickled down to their offspring. Clearly their extremely mesomorphic genetics had combined and been passed down to the next generation. If his 3x great grandfather was a giant, his son, Jeff's 2x great grandfather, was a behemoth. At 6'7" and 330 lbs of pure muscle, he was even bigger than his father, and it seems he joined his parents' sideshow at one point as well.
From here, however, the changes began to taper off. Since Jeff hadn't made any changes to other family members, their genetics began to combine with the mesomorph genes carried in these relatives. His great grandfather was a big man, but not quite like his father or grandfather. Nonetheless he stood at an impressive 6'3" with 280 lbs of muscle and bulk. Not quite the beast his father was, he was nonetheless impressive and put on size quite naturally, both muscle and fat.
Next, Jeff saw his grandfather's profile. Jeff remembered his grandfather as a rather slim man. Even in his old army photos he appeared lithe and lanky, clearly more predisposed to remaining slim despite training and exercise. However, this new grandfather was, in his prime, 6'1 and 220 lbs of athletic muscle, built during his days as an army recruit and maintained through most of his life.
Jeff didn't have to look at the Chronivac as the changes began to affect his dad as his memories of his dad shifted. His dad was still mostly the same, actually. He still worked the same office job and just like before his sedentary lifestyle lent him a mostly average body. The difference now was that instead of the slim mousey look Jeff's dad had before, his frame was generally a little wider and sturdier, if not particularly athletic. At least not anymore. New memories that Jeff didn't recall also formed where his dad had mentioned playing sports in high school, whereas previously his dad had never mentioned sports, but it was clearly not something he kept up with. His dad was also a little taller than Jeff previously remembered at 6' even.
Finally, Jeff felt his own body begin to shift, if somewhat subtly. Similar to his dad, his frame widened somewhat. His shoulders became a little broader, giving him a naturally more masculine shape. His height also increased to about 5'10", not bad for a 16 year old. He didn't gain any muscle to speak of, but the subtle shifts in his bone and muscle structure gave him a feeling it would lend itself well to putting on muscle if he put in the work. Beyond that, he didn't change much, the alterations he made having been watered down over so many generations. There weren't even any new memories of his life that he didn't have before, beyond his slightly altered appearance.
Nonetheless, Jeff was ecstatic. His little experiment had really worked! And now armed with the knowledge he could change whatever he wanted, Jeff set about making more changes