The only reasons not to tell the truth are (a) you are entering a country in order to carry out a crime, or (b) you are entering a country in order to do something that is not permitted under the terms of your entry permit/visa/whatever. FlyerTalk is the wrong place to get advice on either of those.

If you are not in one of those situations, tell the truth. If you are entering a country with that country's passport, you are a citizen coming home even if that's not where you live right now. They pretty much have to let you in no matter what.