The short answer is “it depends.”
It depends what type of information this is and whether you have lied about it during a pretrial testimony.
For example, let's say that during your pretrial testimony, also known as a deposition or examination before trial, you were asked whether you have ever been convicted of a crime. You answered “No.”
Turns out you were convicted of a crime in the past and lied about it.
At trial, the defense is absolutely within their right to show and highlight this inconsistency even though your past conviction had absolutely nothing whatsoever to do with your current lawsuit. That affects your credibility and the defense can certainly address that.
If there are things you have not been proud of during your life that the defense has dug up, not every one of those issues will be permitted during your trial. The key issue is whether they are in any way relevant and related to the issues or the defenses in your case.
Importantly, the judge must ascertain whether these particular issues bear on your credibility and is directly related to the claims being made by you or to the defenses being raised by the people you are suing.