Talk:Kagamine Rin \ Len/@comment-46.117.17.160-20130927151309/@comment-53539-20130929082331

^Incest is considered bad because it limits the diversity of the genetic make up of the body resulting in genetic diseases being increased. It also weakens the immune system.

http://en.wikipedia.org/wiki/Incest

Its most prone disaster then random mixing of genes from different families and over time creates a backlash of issues. Think of the impact pedigree animals suffer such as dogs and cats, some dog breed are on their way to ruin thinks to inbreeding (though pedigree breeders don't want to admit that).