Read this tip to make your life smarter, better, faster and wiser. LifeTips is the place to go when you need to know about Jealousy and Envy and other Infidelity topics.
Deception plays no role in a healthy relationship. At the same time, there's no requirement that you share everything, or that you give up all private life of your own.
If you have a sexual relationship, your partner is entitled to know if you're using birth control, or if you have a sexually transmitted disease. Your partner is not necessarily entitled to know how many people you've slept with in the past. It's OK to draw a boundary and say "I'm not comfortable talking about that. Those things are over, and I'm here with you now, and I'd much rather talk about us."
At the same time, if you're contemplating marriage or children with someone, it's a red flag if you don't know anything about his or her past or family. (Such a person may be concealing an unresolved marriage, a prison record, or even his or her identity.)
As relationships develop, partners may come to agreements around privacy, perhaps agreeing not to read one another's e-mail or to trust each other with personal information that wasn't appropriate to share early on. The important thing is to make these decisions together.