A man has been found guilty by a district court jury of incest - but his co-accused, his daughter, has been acquitted of the same charge.

The pair, who have name suppression, met after the woman went looking for her biological father in Britain. When she finally met the man they began a consensual sexual relationship which spanned 10 years.

To find the man guilty the jury had to be convinced there was a biological connection between the two, that they had sex, and that he had sex with her knowing she was his daughter.

For her to be acquitted, jurors must not have been satisfied that she had sex with him knowing that he was her father. During the trial the court heard that the man told her he doubted he was her father when they first met.

The man will be sentenced in the Auckland District Court on August 20.