Yes, this is how most bird flocks propagate their flocks, especially during times or areas when other swan families or flocks are scarce. Many bird flocks began and continue to survive based upon interbreeding among family members.

Unlike mammals, where genetic anomalies can appear very quickly in the genetic pool, these genetic mutations do not seem to be a problem in Avian (bird) populations. This is not to say that it could never happen, but it is such an infrequent occurrence that it is not considered an issue.

On another note, it was at once thought that swans would not begin to pair and mate until 3 years of age.

However, in our experience with more than 40 years of swan research (swan veterinarians and our other team members), (all species of swans, captive and wild), we have seen siblings begin to pair and actually mate at one year of age and begin mating at 2 years of age.
Although, this early mating may or may not produce viable (fertile) eggs until the 3rd year or later. The Regal Swan
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