Yes, I suppose - if you don't want to go then quit.

In the case of Oleg Kononenko (5 trips to space) that the parent mentioned, while one assumes he could quit if he wanted to, I doubt he keeps getting sent because he's the one begging hardest to go back ... more likely the Russians want to be able to claim space achievements, and "most time in space" is one they can at least achieve, as long as they have a place to send him.