seems to be something I hear many individuals report. Many say they never had motion sickness as a child, but once they hit their 20s and 30s they began to not be able to tolerate motions such as riding on rollercoasters, in the back seat of a car or in a boat. So why does this occur?
I think one reason could be do to genetic changes that occur in our vestibular system over time. Another possibility is we become less mobile as we get older. If you don't use the vestibular system, it will adjust to a less mobile lifestyle. If you don't us it you lose it. As kids, many of us would spin around, twirl, dance, run, skip, roll and tumble. We would play games that would make us fight through spatial disorientation for fun. Once we become older, many of us stop "playing."