No, but generally speaking if you believe in something you are a lot more likely to practice it...or to at least have tried it. That's the whole point of the FML. He believes there is nothing wrong with sibling incest and he has sisters. How can the OP be sure that he hasn't done it?

Morals.

Morals are literally a collection of opinions about what is wrong and right. It's hard to find anything more subjective.

Even if we go to kids - Yes, the chance is higher, but it's not "Oh no they WILL have problems!"-high. A woman who's a bleeder, on the other hand, will habe all her sons be bleeders, too. Or heck, anyone with a dominant genetic disease or disability, yet they *are* allowed to have children. The problem with going down that road is always the question, how far do we go? Do we still allow older women to be mothers due to a higher chance? Do we allow people with depression? Overweight people? Where do we draw the line who's still allowed to have children? I do see different problems with it. The older sibling *might* be in a slight position of power, so it has similar problems as e.g. teachers do, but that's still a pretty big "might", and funnily enough that's never the part people seem to complain about when discussing this topic, whether in fiction nor in real life (Nor do people complain that often about a teacher/student romance in fiction, for that matter).

Morals are not a choice of opinions, morals are a inherent sense of right and wrong which is influenced but not defined by social standards, culture, ones conscious, decency etc. It's no wonder people of today are so ****** up if they don't or can't understand that.

Okay, that is factually incorrect. Morals are NOT an inherent part of humanity. There something that people are raised with them so thoroughly intertwined through daily life that it SEEMS inherent. EMPATHY- the basis for most morals- IS inherent, unless the person is a person born with Anti Social Personality Disorder. Empathy can also be damaged, which is the case with people who has Anti Social Personality Disorder as a result of emotional or physical trauma. Morals, ethics, and customs are the things that society relies on to keep from falling down around our ears. The fact that we're biologically wired not only for empathy (for those without ASPD) but to crave social interaction is why societies eventually developed morals, ethics, and laws. If morals were inherent, then there wouldn't be serial killers, people like Nazis, rapists, child abusers because they would be mentally unable to comprehend the idea of partaking in such acts.

Yep... I don't think sex happening between two consenting adults is that bad just because they're siblings, either. I also have an older brother. There's no way in hell I'd sleep with him. He's a great guy, but he's my *brother* to me and *nothing* else.

Why are people disliking this comment, I thought the joke was funny. I've seen a lot lately that people dislike sarcastic joke comments.