The following is a moral case study. In our society, as in almost all others, incest taboos are strict. Sexual or marriage relationships between close relatives are prohibited.
Engaged couple discover they are brother and sister when their parents meet just before wedding. This woman was expecting a child from her fiancé, and they were looking to get married, until they discovered they are brother and sister. They decided to split, and are highly traumatised.
The problem with taboos is that they come from an often legitimate concern, and resolve that fear by making a set of rules indisputable. Here, avoiding inbreeding is reason enough to condemn all incestuous relationships. If our moral code only tried to prevent inbreeding, enabling rational decisions, the family mentioned should have made a point of staying together. Though in retrospect, she should have avoided having his child, the forward-looking imperative would be to continue a loving relationship with partner and child.
It is unlikely that the incest taboo will weaken soon, but we should at least try to broaden our horizon when faced with decisions. If only the close friends and relatives of this family were rational and supportive, a surprisingly positive outcome for this story would have been possible. As it is, nothing about the news story is remarkable, as no one questions fate imposed by popular sentiment.
Julia Galef collects a list of such unpopular ideas. Though this list is not meant to reflect the wishes or beliefs of her or any one person, I find that I agree with and value many of the points. I highly recommend you go over the list yourself, recognise your doubts, and try to update your beliefs.