Results show the human body changes, but not dramatically.
Here's how fetus in fetu happens.
It all started with two sperm and one egg.
Our editors scrounged up some truly bizarre facts.
And didgeridoos appeared twice.
What does that mean for you?
Mark and Scott Kelly are giving scientists a unique look at what space does to the human body
The next step is to figure out how to flip it
Fertility treatments are a likely factor
Twins Mark and Scott Kelly are key to understanding how space impacts our bodies
Like science, tech, and DIY projects?
Sign up to receive Popular Science's emails and get the highlights.