To mate together closely related cats, for example brother and sister, or father and daughter.

the interbreeding of closely related individuals. This can be used to bring out desirable traits in a species but it can also result in many physical deformities in the offspring. Inbreeding should not be attempted unless you are a highly experienced breeder and know the genetic history of your finches.

To mate closely related individuals

To breed in and in. See under Breed, v. i.

To produce or generate within.