Love and Incest with consent. Incest between consenting family member, Bro/Sis. Son/Mom. Daughter/Dad. Or even learning sex together should be permitted. It often is an excellent expression of
love! I don't think the genetic problems are really significant. Freedom of expression of love and sex should be free. Sons in love with Moms, Daughters in love with Dads should have
sex if consensual. Brother and sister connections are wonderfully satisfying.
As for cousins -- Don't even worry.
Unfortunately the Laws are antiquated.
Probably a brother and sister who were raised together should not be engaged in a physical relationship or marry. But half siblings who weren't raised together and cousins on all levels can really love one another and even marry. The issue of children probably is not that big a deal either, accoring to scientists.
Incestuous couples can of course love each other however that does not make it the right thing to do. They should understand that their actions could result in inbreeding, creating defects and unhappy children. They could maybe have a relationship, but should not reproduce and instead seek methods like adoption.