Incest should not be illegal.

No, It should not be permissible in society. There are multiple things I'm going to challenge you on in your claims because I have a different opinion on them than you. You said "If your argument against incest is purely on reproductive grounds, You have insufficient grounds to make incest illegal" but most of your argument is based around reproduction so why can my counter debate not be about reproduction? "The act of incest in and of itself does not require the participants to have a child" no it does not but accidents happen all the time and then a baby is living a deformed life because you wanted 5 minutes of pleaser with your relative. "Uncles and nephews" this would mean that they are gay and I don't agree with this principle sex is between a man and women for a love connection and an offspring. "While contraception nor sterilization are 100%, Abortions may be used to cover the remaining low-probability conceptions" abortion is murder so for you to go out and have relationships with a relative for pleasure and then have to go rip a kid out of the womb is despicable. "There are couples living today who are aware they have a high percentage chance to conceive children with mental or physical defects and yet they are allowed to have sex. " "There is no requirement for couples to be tested before they have children. The first child's chance of defects is usually unknown before tests may be done in the womb or after the child is born. However, There are many couples who know their next child will have a high chance to have handicaps of some sort yet they still have sex, And some even still try to become pregnant taking no steps to alleviate this" where is your evidence of this? "However, It is extremely difficult to say that incest babies having a slightly higher chance of defects (first generation) than non-incest babies" no it is well know and proven that this is the case and the reason being that if you got a bad DNA jean from your mother and she got it from her mother and then that means your first cousin would have a high chance that she has the bad jean then you have a kid with your first cousin the jeans that need two strands of the same jeans to cause a defect in the child will be made this is just due to probability and the ones that don't need two of the same DNA jeans it still makes the probability of it go higher. Such as down syndrome lets say the 21 chromosomes was carried by a mother but she did not get down syndrome because she had a 50% chance to get it but her son got the carry down but also didn't get it due to the 50% chance but then they both conceive a child the child now has a greater chance if not 100% because there is not another branch that they are able to receive of course I'm talking about the trisomy 21 the down syndrome that can be inherited. Now for the part, You want so badly the support for it while not saying it's about reproduction in which you hardly said anything about and give a reasoning. The reason we have sex other than reproductive reasons is not exactly known yet by scientist just like another simple day to day thing humans do such as sleeping. Most sex done right now is actually not for reproduction purposes but for what? In fact, Most sex lives are better than before they had a kid why? Probably because they're not worried about a little Jimmy popping out in 9 months anymore. But the argument of why they still have sex knowing they can't have a kid anymore is still present. The research shows that sex is not just for reproduction if this were the case why would people do oral or anal or masturbate and saying that it's just for pleasure is not an actual standpoint sure its a factor but not the full reason this is why you don't just have a bunch of men choking the chicken instead of dealing with a nagging women or even paying big bucks for prostitution while also having a high known risk of getting std's so this leads to the conclusion that we have sex for another reason as well and probably the biggest reason a bond between two people. This is why with knowledge of not being able to have a kid or trying we still have sex and also the reason that men love to hear a girl moan because this is a trigger in the brain saying your doing a good job and they are getting off meaning you are having a more connection with the person and raising the emotional state of the encounter, This is also the reason that relationships that are falling apart do not have sex because they are not in love anymore and the bond is broken, Also that being said if you are not having sex in a relationship for awhile then you become less of one and the bond seems to be distant this is why no sex can damage a relationship. Knowing the reason we have sex other than having a child is now to have an emotional bond between one another, The principle of having a different relationship and bond with a relative than what is already present is not justifiable. Sex is a sacred action as stated by a bond previously and so for you to manipulate a bond of just being a cousin to a bond of sex and love it undoubtedly manipulating the role of the previous relationship of just cousins. As another note, There are over 7 billion people in this world and to pick a relative to share this bond with out of anyone is not and should not be socially accepted. Thank you for your time.