A judge who compared incest and paedophilia to homosexuality when he rejected evidence of sexual abuse by a man against his sister was "clearly in error" and the trial should be heard by a different judge, an appeals court has found.

Separately, this month, District Court Judge Garry Neilson was referred to the NSW Judicial Commission and stood down from new criminal trials after the Herald revealed he said the community may no longer see sexual contact between siblings, as well as between adults and children, as “unnatural” or “taboo”.

Judge Garry Neilson in 2003. Credit:Law Society Journal

Judge Neilson made the comments in April during the case of a 58-year-old man, known for legal reasons as MRM, who is charged with repeatedly raping his younger sister in the family's western Sydney home in 1981.

MRM has pleaded not guilty to the charge of sexual intercourse without consent and an alternative charge of incest.