Would your Puppies Come out deformed if a brother and Sister dog had sex?

Would your Puppies Come out deformed if a brother and Sister dog had sex?Is It true, if your two dogs were brother and Sister and had sex. Will they have deformed puppies? Please Help!!!

They puppies could be deformed and will definitely be weak, unhealthy, and can easily get illnesses. It is a really bad idea to interbreed.

What you're talking about is inbreeding, and most pedigree dogs are already very inbred. In the wild, wolf packs are often very inbred because of the small population size. Inbreeding is used by breeders to fix desirable traits, which is why we now have lots of different breeds of dog. The downside is that undesirable genes also become widespread in the population. So a very inbred population might start to display inherited abnormalities, poor immune systems, reduced fertility, and so on.But these are things that only show up with successive increasingly inbred generations that don't receive an influx of new genes. It's very unlikely there would be anything catastrophically wrong with the litter from one particular instance. In a worst case scenario, if both dogs were carrying the recessive for a fatal condition it would show up in roughly a quarter of the litter (with about half being carriers). Nevertheless it's not something one should arrange deliberately, because it's much better for the gene pool to encourage some diversity rather than fix undesirable traits. And it's generally better to breed by design rather than let nature take its course: this certainly isn't something that should be allowed to happen by accident, and it's best to keep fertile females away from males while they're in season.