A question was asked on a forum which read:
"Is it wrong to get pregnant by your own brother or father?"
I answered as follows:
"I shan't delve into the obvious cultural problems arising from such a circumstance; therefore, I shall stick to the biological.
Your brother and father share your DNA if they are your biological brother and father (which I can only assume). Your genetic data requires a completely different set of genes to produce a viable offspring. Viable offspring means a child that has more of a probability of being mentally and physically healthy.
Children born of incestuous unions are more than likely to be deformed or mentally impaired. Some outwardly do not have any signs of problems, but the genetic issue remains. That's why it is a very bad idea to have sexual relations with, and produce offspring with one's family.
If you or anyone you know has become impregnated by a member of your immediate family, you must contact your local authorities. For, especially if pregnancy occurred while the person was underage, this is sexual and child abuse not to mention other criminal offences.
Good luck."