Consensual Incest and Abortion

Several news sources have reported on the German couple -- a biological brother and sister who did not know each other growing up -- who have four children and are pressing for the right to keep their family together.

 

From BBC News, Couple stand by forbidden love:

Patrick, who is 30 years old, was adopted and, as a child, he lived in Potsdam.

He did not meet his mother and biological family until he was 23. He travelled to Leipzig with a friend in 2000, determined to make contact with his other relatives.

He met his sister Susan for the first time, and according to the couple, after their mother died, they fell in love....

Patrick and Susan have been living together for the last six years, and they now have four children.

The authorities placed their first son, Eric, in the care of a foster family, and two other children were also placed in care....

Incest is a criminal offence in Germany. Patrick Stuebing has already served a two-year sentence for committing incest and there is another jail term looming if paragraph 173 of the legal code is not overturned.

The couple's lawyer, Endrik Wilhelm, has lodged an appeal with Germany's highest judicial body, the federal Constitutional Court in Karlsruhe, in order to overturn the country's ban on incest.

See also Siblings fight Germany's incest law (United Press International); German Incest Convict to Take Case to Highest Court (Deutsche Welle).

Many anti-choice people think abortion should be permitted in cases of incest.  Most lump this together with rape as in, "I favor exceptions for rape and incest," appearing to view the two acts as falling within the same general classification.  One reason may be that they view both situations as ones in which the woman is not morally culpable for the procreative act.  But that would imply nonconsensual incest, which doesn't seem to apply to this German couple.  So would they favor an abortion in this context too?

Either way, the position seems to be less about protecting "unborn life" as much as it is about either punishing (or forgiving) the woman in the procreative act (consensual intercourse vs. rape or nonconsensual incest) or about revulsion regarding the procreative act.  It presumably is not a concern for avoiding the birth of children with disabilities, for most anti-choice advocates oppose abortion for reasons of fetal anomaly.  Is there a consistent moral justification that explains an exception for consensual incest?